ASA Statement on Climate Change

Adopted 11-30-07 by the ASA Board of Directors

The American Statistical Association (ASA) convened a workshop of leading atmospheric scientists and statisticians involved in climate change research. The goal of this workshop was to identify a consensus on the role of statistical science in current assessments of global warming and its impacts.

Of particular interest to this workshop was the Fourth Assessment Report of the United Nations’ Intergovernmental Panel on Climate Change (IPCC), endorsed by more than 100 governments and drawing on the expertise of a large portion of the climate science community.

Through a series of meetings spanning several years, IPCC drew in leading experts and assessed the relevant literature in the geosciences and related disciplines as it relates to climate change. The Fourth Assessment Report finds that “Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising mean sea level. … Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations. … Discernible human influences now extend to other aspects of climate, including ocean warming, continental-average temperatures, temperature extremes, and wind patterns.

The ASA endorses the IPCC conclusions.

Over the course of four assessment reports, a small number of statisticians have served as authors or reviewers. Although this involvement is encouraging, it does not represent the full range of statistical expertise available. ASA recommends that more statisticians should become part of the IPCC process. Such participation would be mutually beneficial to the assessment of climate change and its impacts and also to the statistical community.

The US government’s Climate Change Science Program (CCSP) is in the process of producing a set of 21 Synthesis and Assessment reports on many different aspects of climate change. Some statisticians have been appointed members of CCSP committees or reviewers through the National Research Council.

ASA recommends that there should be greater involvement by statisticians in future reviews of the state of climate science conducted by the CCSP. Although there are numerous opportunities for increasing the participation of the statistical community in the IPCC, CCSP, and other assessment processes, the ASA notes that there is already extensive and healthy collaboration between statisticians and climate scientists in basic research on climate change. Furthermore, climate science continues to offer many statistical challenges that are currently not being tackled and many opportunities for collaboration with geoscientists.

The ASA strongly urges statisticians to collaborate with other scientists in order to advance our understanding of the nature, causes, and impacts of climate change.

The workshop convened by ASA identified several specific areas where statistical science can make a contribution. Besides the obvious benefit to the geosciences these topics may well push the boundaries of statistics and suggest new methods, algorithms, and theory.

Interpreting and synthesizing climate observations

Observational data from different measurement platforms and sensors, such as satellites, weather balloons, surface stations, or ocean drifter buoys often represent climate processes at very different spatial or temporal scales. Moreover, observational records from earlier parts of the 20th century are sparse, particularly in southern oceans and in the developing parts of the world. Even in the satellite era – the best observed period in Earth’s climate history – there are significant uncertainties in key observational datasets. Reduction of these uncertainties will be crucial for evaluating and better constraining climate models. Statisticians can advise on how best to combine data from different sources, how to identify and adjust for biases in different measurement systems, and how to deal with changes in the spatial and temporal coverage of measurements.

The climate science community often requires regular fields of geophysical variables, such as surface temperature, which must be derived from irregular and heterogeneous observations. Evaluating the advantages and disadvantages of different interpolation approaches (referred to as infilling in climate applications) could be very helpful. This research area contains many opportunities for the development and fitting of sophisticated space-time models to sparse data.

Climate models

Complex computer models based on physical laws are used to simulate the dynamics of the Earth’s atmosphere, ocean, and sea ice. These models provide a basis for exploring the physical relationship among different components of the climate system and also for making projections of future climate states. The design and analysis of computer experiments is an area of statistics that is appropriate for aiding the development and use of climate models. Statistically based experimental designs, not currently used in this field, could be more powerful. It is also important to understand how to combine the results of experiments performed with different climate models. Despite their sophistication, climate models remain approximations of a very complex system and systematic model errors must be identified and characterized. Model evaluation is an area of active research, with many opportunities for informed statistical input. Finally, assessing the many sources of uncertainty in climate projections requires innovative techniques for better quantifying and, where possible, reducing these uncertainties. Quantifying uncertainty and formal assessment of confidence intervals on observations and model projections are core activities of statistical science, and become particularly appropriate when climate models are used to identify human effects on climate or to estimate climate-change impacts.

Regional and local effects of climate change

There is great need for taking coarse-resolution projections from global and regional climate models down to estimates for small areas. Indeed, translating the large scale understanding of climate processes to changes at a local level is a grand challenge in climate research. Statisticians can provide valuable input to this problem of downscaling climate-model results to the much finer levels of detail required for policy makers.

High dimensional data analysis

The results of climate models and current observational data sets are extremely multi-dimensional and difficult to visualize and analyze. A commonly-used technique is principal components analysis (often known as empirical orthogonal functions analysis in the geophysical sciences). This standard method can miss the nonlinear and non-Gaussian attributes often associated with geophysical processes. Statisticians have the opportunity to contribute improved analytic techniques for interpreting geophysical data. It is very difficult to present all of the information concisely in a manner that can be understood by decision makers. Dimension reduction and data presentation techniques are needed for comparing spatial maps, explaining what is being presented, and determining how to describe the confidence levels associated with projections obtained from noisy and spatially incomplete data.

Human health effects of climate change

The available evidence suggests that certain extreme events with the potential to impact human health may be increasing in frequency as a result of global warming. For example, the IPCC concluded that there have been more intense and longer droughts, and an increase in the frequency of hot days, hot nights, heat waves, and heavy precipitation events. Climate change can also impact human health through its effects on the vectors carrying diseases, or through the complex interplay between large-scale warming and local air pollution. Links between local air pollution and human mortality are already well-established. One issue that has emerged in recent research is the extent to which individual extreme events, such as the 2003 European heat wave, can be attributed to global warming as opposed to other possible explanations, including natural causes. A fruitful line of research is to explore how concepts borrowed from epidemiology, such as relative risk, are potentially valuable in this context. Papers along these lines have started to appear in the climate literature, but there is much scope for further development.

ASA Statement on Climate Change

I'm not a scientist

Climate scientists are certainly seen by most laypeople as boring, and sometimes even irrelevant, when they describe increasing concentrations of atmospheric carbon dioxide, and other “greenhouse gases,” the decreasing pH of oceans, Milankovitch cycles, climate forcings, positive and negative feedbacks, etc., without saying why we should care.

 But when these same scientists put their findings in context relative to current and projected consequences of global warming, e.g.: melting ice sheets and rising sea levels, the bleaching of coral reefs and die off of the aquatic life they support, extended droughts, dwindling ice pack, water shortages, increased prevalence and extent of wildfires, extreme weather events, and the attendant human and economic impact of anthropogenic global warming, they are labeled, "alarmists."

If climate scientists venture to suggest government action to address climate change, politicians (primarily but not exclusively on the right) tell them to stick to the science and leave policy to the "experts," that is, politicians. These same politicians when pressed on why they refuse to address global warming invariably begin their reply, "I'm not a scientist..." My response to that sort of dissembling is, "Then shut the fuck up and listen to the scientists."

Charleston 2107

Greetings from Charleston's Under Water Future
Lindsay Koob
Charleston City Paper , September 12, 2007

Market Street, Downtown Charleston S.C. in 2012

 Imagine the year is 2107, and you're a tourist in Charleston. But instead of a horse-drawn carriage, you're cruising down what used to be Broad Street in a slow-moving tour boat. The water's nine feet deep, and it's only just past low tide. It's high summer, and the base temperature outside your enclosed, climate-controlled boat is pushing 105 degrees Fahrenheit, not counting the 20-degree heat index. The boat drifts past the ruins of St. Michael's Church, with its gaping, glass-toothed windows and collapsed steeple, as the tour guide drones on about its rich history and the last services held there back in 2053 — the church's 300th anniversary — before the rising waters drove its last parishioners to higher ground. The guide reminds you of the great global climate change exodus that began in earnest that decade, with nearly a billion refugees from coastal regions everywhere on top of untold millions of climate-related deaths.

As historic pre-flood photos flash across your seat's video screen, the guide recounts the city's valiant struggle against the ever-rising tide: all the elevated roads, storm sewers, massive pumping systems, canals, and seawalls. And for awhile, they kept pace, that is until the 2040s, when the burgeoning collapse of polar ice sheets drove sea levels to rise more than half a meter per decade. Then in 2046, mega-hurricane Jonah scored a direct hit, devastating the city. The last state and federal insurance props fizzled out, the tax base withered, support and service infrastructures ground to a halt, and the city's economy collapsed. The mega-bucks needed to wall off the sea simply weren't there. By 2050 Charleston had become a half-drowned ghost town.

Since you embarked on your boat tour of sunken Charleston, you haven't seen a seabird all day, and you ask the guide why. He explains that nobody's seen a pelican or a seagull in 40 years, since the marshes drowned. He reminds you that the seas are practically sterile — too acidic and warm to support most sea life — while most of the world's coral reefs are dead. Even the plankton are nearly gone.

By now, you've turned onto the East Bay Canal, passing by the half-collapsed shell of the old Custom House. The water reaches almost to the top of the front steps. The tour ends, and the boat picks up speed, heading out from the sunken city into open water, under the old Ravenel Bridge — now a bridge to nowhere. At least something around here survived intact. Too bad the beautiful old town didn't.

According to the Clemson Architectural Center, if the sea rises 1 foot, 3.5 percent of the Peninsula will be underwater. A sea level rise of 3 feet will cover 9 percent, while a rise of 6 and 12 feet will cover 34 and 77 percent, respectively.

Sure, it's a chilling scenario — but not as far-fetched as you might imagine. It wouldn't be the first time the Lowcountry's been underwater. Just a few weeks back, they found a primeval sea-turtle fossil in a Summerville ditch, and you can dig up ancient petrified sharks' teeth and other marine fossils everywhere along the coastal plain. If only it was geologic time we were dealing with. But now we are learning that our unchecked energy consumption — led by manufacturing, consumerism, and plain old convenience — has compressed eons of climate change into mere centuries, or perhaps even decades. And the heat is on.

Climate Change – Where We Stand

Fifty years ago, nobody listened to the first warnings about pollution-induced global warming and its consequences. But lately, credible scientific evidence has steadily mounted, and what was once theory — or the sky-is-falling cries of a few environmentally-minded Chicken Littles — is now coming true. The United Nations' four-part Intergovernmental Panel on Climate Change (IPCC) report on global warming offers the most credible global confluence of scientific findings and opinion to date (www.ipcc.ch). It zeroes straight in on our wasteful consumption of fossil fuels as the certain cause of our woes.

And the world keeps getting hotter, thanks mostly to our cars and power plants and the vast volumes of greenhouse gases they emit. Yet we still continue to stoke the very atmospheric cooker we're now stewing in. And here, in the land of the figuratively free and the home of the Hummer, we're the world's greediest energy gluttons, gobbling up more fossil fuels and farting out more greenhouse gases than any other nation (though China's catching up fast). And greenhouse gases just don't go away either; most of what we spewed out a century ago is still here and will remain with us for centuries to come. At this point, we can only hope to slow it down enough to avoid the worst of the many possible consequences.

Despite the fairly conservative IPCC predictions, some of our leading scientists are telling us that we're teetering on the brink of self-inflicted climate disaster. Unless drastic action to curtail emissions is taken globally — and soon — rapidly rising atmospheric temperatures (like 6 degrees Fahrenheit) are inevitable by 2100. This in turn will increase oceanic evaporation, boosting torrential rains and flooding in many parts of the world. The higher temps will also dry out topsoils worldwide, spreading drought and deforestation and causing more wildfires.

The growing heat will give rise to a chain of vicious cycles, including runaway melting of permafrost in Arctic regions, releasing vast new quantities of greenhouse gases, especially methane, that will trap even more heat. If ocean temperatures rise, frozen methane hydrates at the bottom of the sea could also melt. According to the U.S. Geological Survey, a concentration of methane off the coast of the two Carolinas is composed of "1,300 trillion cubic feet of methane gas, an amount representing more than 70 times the 1989 gas consumption of the United States." Also, as more carbon dioxide dissolves into seawater, the ocean's acidity level rises. That and other factors have already transformed once vibrant, marine-life sustaining coral reefs into dead, skeleton-white graveyards. If the temperatures continue to rise, plankton — the very base of the aquatic food chain — will also be affected, spelling the potential doom of all sea life. Saying, "Sorry, Charlie," just won't cut it.

On land, hotter weather will also mean the disruption of seasonal patterns, destroyed habitats, and ecological imbalances. Native flora and fauna will migrate elsewhere and be replaced by more tropical species. Even worse, mass extinctions, involving untold thousands of species, are possible. Warmer air will also bring warmer oceans, which in turn will spawn stronger, more frequent storms. The disruption of major oceanic currents also threatens major climate shifts. As the oceans heat up, thermal expansion of seawater alone will certainly cause up to 2 feet of sea level rise by century's end.

But the scariest news these days is the increased disintegration and melting of the world's major polar ice sheets, mainly the ones in Greenland and west Antarctica. Based on ongoing satellite studies, scientists like NASA's chief climatologist James Hansen, have lately reported that the volume of ice surging into the seas has roughly doubled every five years since 1995. If this trend continues unchecked, Hansen says we could well see an additional sea level rise of up to four meters (13 feet), or even more, by 2100.

If such dire predictions come true, the world can kiss its low-lying coastal regions goodbye: places like Holland, Bangladesh, Shanghai, and Venice — not to mention Manhattan, New Orleans, parts of San Francisco, a big chunk of Florida, and Charleston.

According to Jeremy Weiss and Jonathan Overpeck at the University of Arizona, As the sea level rises, from 2 to 6 METERs, Waters will overtake the Charleston area.

Prospects for Charleston

Let's consider what all this means for us. Charleston lies about eight feet above sea level. Just think about the heavy street flooding we get whenever torrential rains come on top of high tide. Sooner or later, a Category 6 hurricane (hey, they're talking about rising ocean temps making those come true, too) could score a direct hit, and a massive storm surge could sweep away half the city.
Even the IPCC's best-case sea level rise of less than a meter will move our shorelines back many hundreds of feet. And that spells likely doom for all the lavish beachfront mansions — and the fragile barrier islands they precariously cling to. All will inevitably succumb to the encroaching surf, and coastal property values will plummet.

With these increasing risks comes the certainty that property insurance will become a scarce commodity. Owners of coastal homes and businesses are already finding that insurance costs are spiraling out of control. This summer's 35 percent hike in state-supported "wind pool" premium rates was no real surprise.

Allison Dean Love, director of the S.C. Insurance News Service, says, "High insurance expense is simply one of the prices you have to pay for the privilege of living on the coast." Most coastal homeowners, she adds, will need as many as six or seven different policies before they can consider themselves adequately covered. You simply won't be able to depend on insurance being there anymore, she warns. Scott Richardson, the state's insurance director, just found that out the hard way when the coverage on his Hilton Head home wasn't renewed.

And then there's the matter of our glorious beaches. A rise in sea level will also cause further coastal erosion, and it won't be long before we have to accept the fact that it is futile to keep renourishing our disappearing beaches. DHEC reports that, since 1990, keeping our beaches well-sanded and tourist-friendly has cost us $144 million. Meanwhile, the Environmental Protection Agency estimates that the overall cost of keeping beaches up to par could top $9 billion this century.

"There's a limited amount of suitable sand for renourishment," says Chris Marsh, executive director of the Lowcountry Institute. "We can't expect it to be available 30 to 50 years from now."

A rapid rise in sea level will also drown our surrounding tidal marshes and wetlands faster than they can regenerate inland, especially where development has gone before. You can't grow new marshes on top of flooded roads and parking lots and subdivisions. And don't forget that marshes are both nursery and larder to thousands of species, including shrimp, crabs and oysters, that will disappear along with them.

The National Centers for Coastal Ocean Science's Carol Auer, an oceanographer who works for the organization's Center for Sponsored Coastal Ocean Research, says a rise in sea level poses great risks to our coastal wetlands. She places much of the blame on runaway coastal development, which often pushes right up against tidal creeks and marshlands. Routinely approved construction of docks and protective bulkheads often leaves the marshes no place to go as water levels rise, gradually drowning them. "Bulkheads are one of the worst things people can do to the coastal environment," she says.

Jim Morris, director of the Baruch Institute for Marine and Coastal Science at the University of South Carolina, says Charleston-area marshes seem to be healthier than those around the Georgetown area he regularly studies, due in part to the relatively large volumes of sediment deposited by the Cooper River watershed. He adds that while it's an off-and-on process, South Carolina's marshes seem to be keeping up with the rising sea levels for the time being. He believes that they could "probably handle a rate of sea level rising somewhat less than 1 centimeter per year" — at least for awhile, and in areas where marsh expansion isn't blocked by heavy development.

Despite what some straw-grasping skeptics would have us believe, there is no real good news to report about global warming. Ben Moore, climate and energy project manager of the Coastal Conservation League, says, "After a certain point, there are simply no positive aspects to global warming."

Bottom line: How can we defend ourselves from 6 feet of standing water in our streets? Not many of the folks I've talked to foresee the kind of political will and thus the funds to build the kind of massive, Netherlands-style dikes and pumping systems that will be necessary to stem the tide. That's because the rise in the sea level isn't likely to stop at just a few feet; barriers and pumping systems will have to be continually expanded and strengthened.

That said, something must be done.

Michael Maher and the folks at the Charleston Civic Design Center, a municipal planning agency, have begun developing programs and projects they think will help us cope with global climate changes. These include the Charleston Green Initiative, which promotes a more resource-efficient approach to municipal operations. "Charleston's a canary in the coal mine of global warming," Maher says. He hopes that gives us the chance to "lead the fight against it."

Then there's architect Robert Miller, director of the Clemson Architectural Center in Charleston. He and his students recently completed a truly impressive project that looks at peninsular Charleston at various levels of future sea level rise: 1, 3, 6, and 12 feet. (The project will be unveiled at the College of Charleston library sometime after the new year.) Various measures designed to deal with each of these successive water levels are then explored. These include fairly simple measures at the low end, like marsh expansion along the city's western shore, and the creation of water retention parks where storm runoff and tidal flooding can be contained until it can be pumped away.

Then, as projected sea levels rise, so does the sophistication, and expense, of the proposed fixes. The construction of elevated roadways, water-absorbing pervious pavement, seawalls, and canals are all explored by Miller and his crew. The ultimate fixes occur once the sea hits the 12-foot level: if that happens, either a walled-city approach that protects only the peninsula or a massive harbor-front levee that will also save surrounding areas like West Ashley and Mt. Pleasant, complete with a system of locks that will permit continued shipping traffic. "At that point," Miller says, "Charleston will be like another New Orleans: an entire metropolitan area lying well below sea level." But who will pick up the mega-billion price tag?

Sure enough, there remain far more questions than answers at this point. And since we, the people, don't yet take the global warming threat seriously, most related research programs remain seriously underfunded, and therefore ineffective. And we're not likely to wake up until after we suffer several painful black eyes at the hands of poor, abused Mother Nature — or a mortal blow to our pocketbooks. Major policy change is seldom inspired by altruism.
______________________________________________
In the seven years since this article was written, CO2 concentrations in the atmosphere have exceeded 400 ppm -- levels unprecedented in recorded human history. China has already overtaken the U.S. in emissions, and the West Antarctic Ice Sheet has started a now unstoppable collapse, with an estimated sea level impact of 12 ft by 2100. Meanwhile, Republicans in Congress are holding hearings to stop the EPA from issuing new regulations on greenhouse gas emissions.

The Hiatus in Global Warming Has Deniers in Paroxyms of Joy; It is However, Unwarranted

From The Economist, March 8, 2014

BETWEEN 1998 and 2013, the Earth’s surface temperature rose at a rate of 0.04°C a decade, far slower than the 0.18°C increase in the 1990s. Meanwhile, emissions of carbon dioxide (which would be expected to push temperatures up) rose uninterruptedly. This pause in warming has raised doubts in the public mind about climate change. A few sceptics say flatly that global warming has stopped. Others argue that scientists’ understanding of the climate is so flawed that their judgments about it cannot be accepted with any confidence. A convincing explanation of the pause therefore matters both to a proper understanding of the climate and to the credibility of climate science—and papers published over the past few weeks do their best to provide one. Indeed, they do almost too good a job. If all were correct, the pause would now be explained twice over.

This is the opposite of what happened at first. As evidence piled up that temperatures were not rising much, some scientists dismissed it as a blip. The temperature, they pointed out, had fallen for much longer periods twice in the past century or so, in 1880-1910 and again in 1945-75 (see chart), even though the general trend was up. Variability is part of the climate system and a 15-year hiatus, they suggested, was not worth getting excited about.

An alternative way of looking at the pause’s significance was to say that there had been a slowdown but not a big one. Most records, including one of the best known (kept by Britain’s Meteorological Office), do not include measurements from the Arctic, which has been warming faster than anywhere else in the world. Using satellite data to fill in the missing Arctic numbers, Kevin Cowtan of the University of York, in Britain, and Robert Way of the University of Ottawa, in Canada, put the overall rate of global warming at 0.12°C a decade between 1998 and 2012—not far from the 1990s rate. A study by NASA puts the “Arctic effect” over the same period somewhat lower, at 0.07°C a decade, but that is still not negligible.

It is also worth remembering that average warming is not the only measure of climate change. According to a study just published by Sonia Seneviratne of the Institute for Atmospheric and Climate Science, in Zurich, the number of hot days, the number of extremely hot days and the length of warm periods all increased during the pause (1998-2012). A more stable average temperature hides wider extremes.

Still, attempts to explain away that stable average have not been convincing, partly because of the conflict between flat temperatures and rising CO2 emissions, and partly because observed temperatures are now falling outside the range climate models predict. The models embody the state of climate knowledge. If they are wrong, the knowledge is probably faulty, too. Hence attempts to explain the pause.

In September 2013 the Intergovernmental Panel on Climate Change did so in terms of fluctuating solar output, atmospheric pollution and volcanoes. All three, it thought, were unusually influential.
The sun’s power output fluctuates slightly over a cycle that lasts about 11 years. The current cycle seems to have gone on longer than normal and may have started from a lower base, so for the past decade less heat has been reaching Earth than usual. Pollution throws aerosols (particles such as soot, and suspended droplets of things like sulphuric acid) into the air, where they reflect sunlight back into space. The more there are, the greater their cooling effect—and pollution from Chinese coal-fired power plants, in particular, has been rising. Volcanoes do the same thing, so increased volcanic activity tends to reduce temperatures.

Gavin Schmidt and two colleagues at NASA’s Goddard Institute quantify the effects of these trends in Nature Geoscience. They argue that climate models underplay the delayed and subdued solar cycle. They think the models do not fully account for the effects of pollution (specifically, nitrate pollution and indirect effects like interactions between aerosols and clouds). And they claim that the impact of volcanic activity since 2000 has been greater than previously thought. Adjusting for all this, they find that the difference between actual temperature readings and computer-generated ones largely disappears. The implication is that the solar cycle and aerosols explain much of the pause.

There is, however, another type of explanation. Much of the incoming heat is absorbed by oceans, especially the largest, the Pacific. Several new studies link the pause with changes in the Pacific and in the trade winds that influence the circulation of water within it.

Trade winds blow east-west at tropical latitudes. In so doing they push warm surface water towards Asia and draw cooler, deep water to the surface in the central and eastern Pacific, which chills the atmosphere. Water movement at the surface also speeds up a giant churn in the ocean. This pulls some warm water downwards, sequestering heat at greater depth. In a study published in Nature in 2013, Yu Kosaka and Shang-Ping Xie of the Scripps Institution of Oceanography, in San Diego, argued that much of the difference between climate models and actual temperatures could be accounted for by cooling in the eastern Pacific.

Every few years, as Dr Kosaka and Dr Xie observe, the trade winds slacken and the warm water in the western Pacific sloshes back to replace the cool surface layer of the central and eastern parts of the ocean. This weather pattern is called El Niño and it warms the whole atmosphere. There was an exceptionally strong Niño in 1997-98, an unusually hot year. The opposite pattern, with cooler temperatures and stronger trade winds, is called La Niña. The 1997-98 Niño was followed by a series of Niñas, explaining part of the pause.

Switches between El Niño and La Niña are frequent. But there is also a long-term cycle called the Pacific Decadal Oscillation (PDO), which switches from a warm (or positive) phase to a cool (negative) one every 20 or 30 years. The positive phase encourages more frequent, powerful Niños. According to Kevin Trenberth and John Fasullo of America’s National Centre for Atmospheric Research, the PDO was positive in 1976-98—a period of rising temperatures—and negative in 1943-76 and since 2000, producing a series of cooling Niñas.

But that is not the end of it. Laid on top of these cyclical patterns is what looks like a one-off increase in the strength of trade winds during the past 20 years. According to a study in Nature Climate Change, by Matthew England of the University of New South Wales and others, record trade winds have produced a sort of super-Niña. On average, sea levels have risen by about 3mm a year in the past 30 years. But those in the eastern Pacific have barely budged, whereas those near the Philippines have risen by 20cm since the late 1990s. A wall of warm water, in other words, is being held in place by powerful winds, with cool water rising behind it. According to Dr England, the effect of the trade winds explains most of the temperature pause.

If so, the pause has gone from being not explained to explained twice over—once by aerosols and the solar cycle, and again by ocean winds and currents. These two accounts are not contradictory. The processes at work are understood, but their relative contributions are not.

Nor is the answer to what is, from the human point of view, the biggest question of all, namely what these explanations imply about how long the pause might continue. On the face of it, if some heat is being sucked into the deep ocean, the process could simply carry on: the ocean has a huge capacity to absorb heat as long as the pump sending it to the bottom remains in working order. But that is not all there is to it. Gravity wants the western-Pacific water wall to slosh back; it is held in place only by exceptionally strong trade winds. If those winds slacken, temperatures will start to rise again.

The solar cycle is already turning. And aerosol cooling is likely to be reined in by China’s anti-pollution laws. Most of the circumstances that have put the planet’s temperature rise on “pause” look temporary. Like the Terminator, global warming will be back.

Hatching a Rotten Egg

Utah’s Republican Sen. Orrin Hatch maintains a web page called “Climate Change 101,” in which he gives some reasons why he doesn’t think anthropogenic climate change is likely to be a problem. The page is riddled with red herrings, references to studies that have since been refuted by other scientists, and the use of fraudulent data.

In his section on Intergovernmental Panel on Climate Change (IPCC) climate models, Hatch reproduces two graphs that were created by Christopher Monckton of the Science and Public Policy Institute, who has no scientific training. One graph purports to show that the IPCC climate models badly over-predicted the temperature evolution over the past decade. The other purports to show that IPCC carbon cycle models have badly over-predicted the evolution of atmospheric carbon dioxide over the past decade.

The graphs seem very compelling, but the fields Monckton labels as IPCC predictions are actually outright fabrications. Check it out here: www.realclimate.org/index.php/archives/2010/08/monckton-makes-it-up/.

From an 11/29/10 article in the Salt Lake Tribune, by Barry Bickmore