Back in March, United Nations officials decided they had to respond to a series of attacks on the credibility of the Intergovernmental Panel on Climate Change (IPCC), which was founded by the U.N. and World Meteorological Organization in 1988. Among other things, critics asserted that the most recent IPCC assessment report, which was published in 2007, contained errors, and that its authors failed to properly assess uncertainties in projections of future climate. Critics also said the IPCC Chairman, Rajendra K. Pachauri, might be guilty of conflicts of interest (an accusation that evidently didn’t have much substance) and more.
So the U.N. went to a body called the InterAcademy Council, made up of representatives from 18 national science academies in major countries including the U.S., France, the U.K., Germany and China. The Council in turn recruited Harold Shapiro, a Princeton economist and the university’s president emeritus, to run an independent investigation.
That investigation is now complete, the report written and the verdict in. “The Committee found that the IPCC assessment process has been successful overall,” says the Executive Summary. "However the world has changed considerably since the creation of the IPCC, with major advances in climate science, heated controversy on some climate-related issues, and an incre...
More on the Sun-Climate Connnection
Graphic of a satellite observing a distant star.
Credit: UCAR/Institute of Astrophysics of the
A brightening Sun has largely been debunked as the reason for rising global temperatures over the past half-century or so. But that doesn’t mean solar changes can’t influence climate. In the first half of the 20th century, in fact, solar brightening may indeed have been a major factor in global warming. Changes in Earth’s orientation to the Sun, meanwhile, are believed to have triggered the start and end of ice ages over the past many hundreds of thousands of years.
More recently, solar physicists have been watching the Sun go through a period of unusual inactivity, with fewer sunspots than normal —which usually goes with an overall Solar dimming. They even thought the Sun might be entering a new version of the Maunder Minimum, when sunspots were depressed for decades, and the world went though an especially cold period that included the Little Ice Age.
It’s not entirely clear what triggered the recent drop in sunspot activity, although solar physicists have some ideas. It’s also unclear whether the even more recent recovery means things are back to normal—but either way, a complete understanding of climate isn’t possible without a good understanding of how the Sun waxes and wanes.
Which is why a new study out of the National Center for Atmospheric Research is poten...
New Study Says Geoengineering Schemes Will Struggle to Reduce Sea-Level Rise
Graphic showing different geoengineering concepts. Credit: Lawrence Livermore National Laboratory.
As we’ve detailed, geoengineering is increasingly being viewed by some scientists, ethicists, and policymakers as an option to seriously consider in order to prevent the most severe consequences of climate change. Various proposals have been put forward, including injecting sulfur dioxide (SO2) into the stratosphere to reflect incoming solar radiation, or launching large space mirrors that would also redirect incoming heat from the sun. Such measures could theoretically cut down on the temperature increase that would otherwise occur due to human emissions of greenhouse gases, such as carbon dioxide.
But could they be effective in preventing sea level rise, one of the most far-reaching and worrisome consequences of climate change?
Not unless you are willing to go all in on geoengineering – while also significantly reducing greenhouse gas emissions – says a new study published by an international team of researchers. The study, published in Proceedings of the National Academy of Sciences, analyzes the effects that five different geoengineering approaches would have on sea level rise, and finds that all but the most aggressive geoengineering proposals would still allow sea level to increase substantially during this century. A key reason for this is that whil...
Get Used to La Nina
Sea surface temperature anomalies for the first week of August,
2010. Blue areas indicate cooler-than-average temperatures.
Red areas are warmer-than-average. The area of cool
temperatures in the equatorial Pacific are characteristic
of La Nina conditions.
Credit: NOAA Environmental Visualization Lab.
Following on the heels of the 2009/10 El Nino event, a moderate La Nina is underway in the Pacific Ocean, and is likely to continue through early 2011, according to an outlook released by the International Research Institute for Climate and Society (IRI) on August 19. La Nina is characterized by unusually cool water temperatures in the central and eastern equatorial Pacific Ocean, and warmer-than-average water temperatures in the western Pacific, with associated changes in air and water circulation. (This is in contrast to El Nino, which features warmer-than-average water in the central and eastern tropical Pacific).
La Nina conditions first emerged in mid-June and have strengthened since that time. Such conditions are evident in the map of sea surface temperature anomalies, or departures from average, below.
Sea surface temperature departures from average during the week of August 18. Credit: NOAA/NCDC.
The unusually warm water near Indonesia is harming coral reefs, according to a report detailed in the New York Times last week. "A striking rise in sea temperatures in wa...
Extra CO2 May Not Be Such a Boon for Plants After All
Back in 2003, Steve Running, an ecologist and climate modeler at the University of Montana, co-authored a paper that analyzed changes in the uptake of carbon dioxide (CO2) by plants around the world (the technical term for this uptake is “primary production”). The paper showed that it had been increasing through the 1980s and 1990s. The reason, he says: “Warming global temperatures were leading to longer growing seasons” – which gave plants more time, on average, to suck in CO2.
Running and his Montana colleague Maosheng Zhao returned to the question recently, and since temperatures have continued to rise, says Running, “our hypothesis was that was that if you’re following the same logic, you should [see] a further enhancement in primary production.”
Instead, according to a new paper the pair authored in this week’s Science, there's been a trend reversal. Specifically, they found that while carbon uptake rose about six percent from 1982 to 1999, it’s since pulled back by about one percent.
“In higher latitudes,” Running says, “we’re still seeing lengthening of growing seasons.” Closer to the equator, though, and especially in the southern hemisphere, the warming has lead to major droughts – not exactly a recipe for healthy plants. What makes this study so compelling is that it was based on global satellite observations, not scattered local measurements. Runnin...