But, it turns out, city dwellers can expect a lot more hot days than country folk, climate models tell us. As the Spoonful put it:
Hot town, summer in the city
Back of my neck getting dirty and gritty
Been down, isn’t it a pity
Doesn’t seem to be a shadow in the city
Their lyrics stuck in my head as I began a week-long journalism fellowship at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, in an attempt to learn more about climate science, extreme weather, geoengineering and space physics.
One of the first things I’ve learned: Projections of global mean temperature increases typically reported in the press–while perfectly accurate–can hide as much as they reveal.
You’ve probably read that temperatures are expected to increase by 1.8 – 4 °C (3.2 – 7.1 °F) by 2100. So, at least, says the 2007 IPCC Report on Climate Change. [Here’s a Summary for Policy Makers [PDF] ] That’s not especially alarming.
As Synte Peacock, an oceanographer and climate scientist at NCAR, told me: “I’ve had so many people say to me, ‘ two degrees, three degrees,’ that’s no problem, I can live with that. But that’s not what they are going to see.”
Instead, many will see dramatic changes. Average temperature increases (like any averages) hide seasonal and regional impacts that could reshape local geographies, not to mention extreme weather events.
“The seasonal changes in Alaska and Canada, they’re going be phenomenal,” Peacock said. “They could be three or four times higher than the global mean.”
“When you go to something like an 8 degree increase, you’re in a totally different world.”
Put another way: like politics, all climate change is local. People don’t care about average temperatures. They want to know what crops will (or won’t) grow in the midwest. They want to know what summer will be like in New York or D.C.
Pretty horrible, it turns out. Cities will likely heat up faster than rural areas, as the chart below shows. [Click to make the image larger.] Ninety-degree days, or worse, will become the norm.
Cities are “heat islands” for a variety of reasons–they have less vegetation, more waste heat from AC and decreased loss of heat through turbulence because of stagnation in urban “canyons,” according to NCAR’s Keith Oleson. His research has found that “painting the roofs of buildings white has the potential to significantly cool cities and mitigate some impacts of global warming.”
The world is, of course, becoming more urban, so the idea that cities will be disproportionately impacted by climate change is anything but welcome news.
NCAR, by the way, is a non-profit institution, home to about 1,000 employees, funded mostly by your tax dollars allocated by federal agencies like the National Science Foundation, NASA, NOAA and the U.S. Department of Energy. It’s part of UCAR, or the University Corporation for Atmospheric Research, (ah, bureacracy) which is itself governed by a board made up of research universities. Besides doing its own research, NCAR and UCAR provide university and government researchers with powerful tools they couldn’t afford on their own, like giant supercomputers and a Gulfstream V plane (that we’ll see tomorrow) that collects atmospheric data.
Today we also learned about NCAR’s climate model, which is one of about two dozen global climate models, scientists said. These models are incredibly complex and entirely dependent on massive computing power because they include so many variables. Without supercomputers, there would be no reliable climate models.
“We’re trying to represent in a numerical model many, many, many processes across a vast range of spatial scales and time scales,” said James W. Harrell, chief scientist for NCAR’s model, which is known as the Community Earth System Model. Here is an oversimplified illustration of factors that go into the model.
I was surprised to learn that, even using some of the world’s most powerful computers, it can take an entire year of computing, 24/7, to run several scenarios through the model. Even then, there are uncertainties, a big one revolving around the role of clouds. Warmer temperatures in the future will mean more evaporation, and therefore more clouds, which have the effect of reflecting sunlight, and slowing the warming trend. By how much? Scientists disagree.
So, yes, as the skeptics like to tell you, the models are imperfect. So are most predictive models–past performance, as we say in the financial world, is no guarantee of future results.
But when it comes to climate, the trends are unmistakable and clear. The scientists here are devoting their lives to trying to refine the models and sift through the evidence, to better prepare policy-makers, corporate leaders and the rest of us for the potentially very risky world that we are making for ourselves. More to come in the days ahead…