ALBUQUERQUE, N.M. — Global warming is unequivocal in its advance and will lead to more record-setting temperatures, said Warren M. Washington, a senior scientist at the National Center for Atmospheric Research, in the seventh lecture of Sandia National Laboratories’ Climate Change and National Security series. The talk was given in mid-May.
Washington, a pioneer in atmospheric computer modeling, served as science adviser to five presidents — Jimmy Carter, Ronald Reagan, Bill Clinton, George H.W. Bush and George W. Bush. He received a lifetime achievement award from then-DOE Undersecretary for Science Raymond Orbach in 2007 and was awarded the National Medal of Science by President Barack Obama in 2010.
Washington presented graph after graph showing how various atmospheric processes have combined to create stronger rainfall near the equator and more intense droughts in the subtropics, as well as sea-level rises and increased storm surges. He said more tropical diseases would move poleward as the tropics expand.
He also envisioned stresses on national security when some island and coastal countries either disappear or sink below sea level because of rising oceans. “Their populations will need to migrate elsewhere, causing immigration issues,” he said.
Basically, he advised, “People shouldn’t be building houses on the seacoast or putting houses in flood plains.”
With a nod to climate-change skeptics, he cited noted University of California-Berkeley professor Richard Muller as a one-time skeptic of the general scientific belief that “we’ve warmed the planet by almost a degree [Celsius] from 1880 to 2010 in the global land temperature average.” Washington said Muller and his colleagues used a different technique to compute Earth’s land temperature, but his graph only reproduced what others found earlier.
In several instances, he challenged climate-change skepticism.
“Climate skeptics often mention that solar radiation has changed and that is what is causing the climate change,” he said as he presented a graph charting the intensity of solar irradiance at the top of Earth’s atmosphere. “You can see 11-year cycles from 1975 on and you can see there is no significant trend on radiation coming into the atmosphere. So this argument by skeptics isn’t valid to the climate change community.”
Meanwhile, he said, extremes in temperature have grown since the 1960s, methane and nitrous oxide concentrations are increasing, ozone depletion is increasing, the usually ice-locked Northwest Passage this fall should be open for shipping if accompanied by an icebreaker and 2010 was “a record year for glacier melting in Greenland, as observed by satellite.”
With some exceptions, he said, glaciers are melting substantially around the globe. “Since the 1960s,” he said, “ocean heat content, humidity, temperatures near just above the sea surfaces and the temperatures over land and oceans have increased substantially. Meanwhile, snow cover, glaciers and sea ice have decreased.”
As for what is causing the changes shown by his graphs, he said, “Natural variations [used in models] do not explain climatic change. Climate model simulations with just natural ‘forcing,’ including volcanic and solar, do not reproduce warming. However, when the increase in greenhouse gases is included, models do reproduce the global warming patterns. We consider this a ‘smoking gun’ proof.”
Adding the effects of aerosols to climate models further improves their agreement with the temperature-warming trends of the last decades, he said.
Slow computing initially handicapped experiments to simulate climate change, he said. Much faster computing speeds have led to more accurate models.
Still, Washington said, international meetings about climate with politicians in Copenhagen, Cancun, Mexico, and Durban, South Africa, “haven’t gotten very far. Basically, there’s a lot of inertia in making big changes in our energy profile.”
He postulated several reasons for this. “Many skeptics claim that climate change is a hoax and we have some sort of secret agenda to fool the public. Obviously, I believe there’s no conspiracy, that climate change is not a hoax and that the advice we give the policymakers is honest and good science,” Washington said.
Later in his talk, he said, “We’re faced by a lot of people whose business interests are affected by climate change mitigation.”
Washington’s simulations showed that cutting back on carbon emissions and concentrations in the atmosphere would help curb future temperature rises. But he called some proposed geoengineering measures unlikely to do much. These include space mirrors to reflect light away from Earth and stratocumulus cloud seeding to brighten them so that more solar radiation is reflected out to space.
He said more realistic possibilities include sequestration of carbon — sending it underground or to the ocean bottom. For the short-term, he mentioned the positive effect of reducing the amount of airborne methane and other non-greenhouse gases such as Freon.
“Climate system models are far from being perfect,” he said, “but are the best indicator of our science knowledge of how the climate system works.”
Sandia scientist Mark Taylor came in for special praise from the speaker for a significant climate simulation on the Argonne National Laboratory supercomputer Blue Gene/P that produced a geographic resolution of 12 kilometers. “Sandia has played a major part in getting the climate community a brand new tool to study climate change,” said Washington.
Later, he said, “Scientists like Mark Taylor and others have turned to techniques like using a cubed sphere grid to make calculations parallel and therefore solvable on modern systems.” Old-fashioned maps showing latitude and longitude converged at the poles, making them hard to work with.
The talks are sponsored by Sandia’s Climate Security Program.