Notes from a Warming World: Spring 2013

New Hot Colors

In January the mercury soared so high Down Under that Australia’s meteorology department added two new colors to its weather map – incandescent purple and pink. Red simply wasn’t hot enough to describe the scorching temperatures the country was experiencing during its hottest summer on record.

The new colors extend Australia’s temperature range to 129°F (54°C), from the previous cap of 122°F (50°C). The nation’s average high temperature exceeded 102°F (39°C) for five consecutive days from January 2 to 6 – the first time that has happened since record keeping began in 1910.

Australian weathermen didn’t pull punches when explaining the cause of the staggering heat. ‘‘Clearly, the climate system is responding to the background warming trend,” said David Jones, the Bureau of Meteorology’s manager of climate monitoring and prediction. “Everything that happens in the climate system now is taking place on a planet which is a degree hotter than it used to be.’’

image of a color-coded heatmap, showing the continent of Australia Purple is the hot new color for summertime.

Scientists have already shown that climate change exacerbated the European heatwave of 2003 that caused an estimated 70,000 premature deaths and the 2010 Russian heatwave that killed 15,000 and destroyed $15 billion worth of crops. If all these warning signs don’t push countries to take drastic action to cut their carbon emissions, soon we’ll need even hotter shades for the weather maps.

Damage Assessment

No new map colors yet here, but the US government’s draft National Climate Assessment report does send out some big red alerts. The 1,146-page report offers official confirmation on what many Americans already have witnessed for themselves: The weather is getting hotter and weirder.

The report concludes that climate change is a serious threat to America’s economy and natural resources and that our continued dependence on fossil fuels is worsening the situation. It estimates that average temperatures in the US will continue to rise, with the next few decades projected to see another 2°F to 4°F of warming in most areas. It details, region by region, how coastlines will disappear, how storms and droughts will become more intense, and how these changes will impact everything from infrastructure to food cultivation to freshwater supplies.

Federal law requires the assessment be produced every four years. The Bush administration, urged on by the fossil fuel industry, tried to suppress the first National Climate Assessment produced by the Clinton administration in 2000, going as far as to edit out any references to it in other official reports. The second assessment, prepared mostly by the Bush administration, required a lawsuit by environmental groups to see the light of day. It was finally published in 2009 – three years late.

Warming from a Distance

Big cities emit a lot of heat. That’s old news. The urban heat island effect – in which heat trapped in large buildings, paved streets, and automobiles makes cities several degrees warmer than the surrounding countryside – is a well-documented phenomenon. But now a new study, published in the journal Nature Climate Change, says that the heat emitted by major metropolitan areas on America’s East Coast is causing winter warming as far away as the Canadian prairie.

Here’s how it works: Excess heat from cities appears to change air circulation patterns, then the hot air hitches a ride on air and ocean currents, and eventually affects the temperature someplace else. Remote locations can heat up by as much as 1.8° F as a result.

The study found a similar pattern in Asia, where major population centers are warming up Russia, northern Asia, and eastern China. But the same phenomenon seems to have an opposite effect in Europe, cooling off some of its regions, especially in autumn. Basically, the excess heat can change atmospheric patterns to either raise or lower temperatures far afield, says study co-author Aixue Hu of the National Center for Atmospheric Research in Colorado. The impact of this heat on mean global temperatures is negligible – barely .01°C. But it does have a noticeable impact on regional temperatures. The new finding could help explain why some places are warmer in winter than climate computer models predict. “What really surprised us was that this energy use was a tiny amount, and yet it can create such a wide impact far away from the heat source,” says Guang Zhang of the Scripps Institution of Oceanography.

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