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A look at weather extremes and the big-picture climate connections.

Historical Perspective on the Russian Heat Wave of 2010

By Heidi Cullen and Claudia Tebaldi

The summer of 2010 brought intensely hot weather to large portions of the northeastern U.S., central Europe, and Russia. Russia was especially hard hit as a heat wave — with daily high temperatures hitting 100°F — contributing to the deaths of as many as 15,000 people in Moscow while wildfires tore across more than 2,900 square miles in the central and western part of the country. Drought accompanied the record high temperatures decimating more than a quarter of Russia’s grain harvest. Economists estimated the grain losses cost the Russian economy upwards of $15 billion dollars.

As climate scientists continue to study the underlying dynamics of this extreme heat event in order to better understand the extent to which human-caused climate change may have played a role, we wanted to put the Russian heat wave of 2010 into historical context. With that in mind, we collected temperature data from Moscow for July 2010 as well as summer (June through August 2010) and compared it to every year since 1950. (Our analysis is similar to that employed by Schär et. al in their 2004 Nature paper). 

We sought an answer to the question: how significant was the departure of the 2010 values from the typical summer temperature in Moscow?

Probability of June, July and August average temperature anomalies in Moscow, Russia since 1950.
This image shows that the average temperature in Moscow for summer 2010 was significantly hotter than...


Eyeing Super Typhoon Megi

By Andrew Freedman



Satellite image of Super Typhoon Megi as it approached the island of Luzon in the Philippines on Oct. 18.
Credit: CIMSS/University of Wisconsin.

Every once in a while an image comes along that perfectly captures an awe-inspiring force of nature, such as a hurricane or tornado, in a way that makes it seem beautiful rather than devastating or terrifying. Today a satellite image came across my Twitter feed (hat tip to Brad Panovich, chief meteorologist at News Channel 36 in Charlotte, N.C.) that immediately grabbed my attention. It comes from NASA's Terra satellite, which carries an instrument called a "Moderate Resolution Imaging Spectroradiometer," or MODIS. The MODIS image above shows cloud-top temperatures in Super Typhoon Megi as it approached the island of Luzon in the Philippines earlier today, packing sustained winds of 165 miles per hour with higher gusts. 

Megi caused significant damage across the island, and is now back over ocean waters and heading for a second landfall in mainland China.

The picture shows the storm's extremely well-defined eye and the towering thunderheads surrounding it, which is where the storm's strongest winds can be found. The colors correspond to the coldness of the cloud tops, with the purple regions just to the south of the eye, as well as to the east/southeast, showing an infrared brightness temperature as low as -82°C, which corresponds to an area of especially intense precipitation an...


Arctic Tipping Points Affect World Climate

By Gretchen Weber, KQED ClimateWatch

The Arctic is warming, and what happens there has consequences for California.

Photo: Gretchen Weber

During the two weeks I spent in the Arctic at Toolik Field Station this summer, there was a lot of talk about positive feedbacks and how what happens in the Arctic can affect the entire planet. Thawing permafrost, which I explore in my radio piece for The California Report, is cause for some of the greatest concern.

Another is the loss of sea ice. Mean summer temperatures in the Arctic have risen about three degrees Fahrenheit since 1960, and summer sea ice is shrinking more than 11% per decade. This year ranks third for the minimum Arctic summer sea ice extent since satellite record-keeping began in 1979. 2007 and 2008 hold the records, and 2009 is in fourth place.

Shrinking sea ice matters not just because it's an indication of warming, but also because it can accelerate it. Sea ice keeps polar regions cool by reflecting sunlight and heat, which helps moderate the global climate system. When sea ice isn’t there, the sun hits the surface of the Arctic Ocean instead. The ocean is relatively dark in color, so instead of reflecting 80% of the sunlight, it absorbs 90%. This heats up the ocean and the Arctic--which, of course, melts more ice.

Another potential feedback scientists are looking at is "shrubification" (try tossing that one into a conversation), but whether it's a positive or negative feedback remains up for...


Could a Brightening Sun Cool the Earth?

Michael D. Lemonick

By Michael D. Lemonick

We've talked before about the sun-climate connection, which is often invoked as the great missing link in understanding climate change. It's absolutely true that the sun is crucial to Earth's climate. Without it, we'd have no winter, no summer, no day/night temperature variations — and it wouldn't matter anyway, because the planet would be frozen solid. It's also understood that even slight variations in the sun's energy output — which are known to occur — do warm or cool the climate, at least a little. 

But none of that answers the question of whether the current warming of the climate is mostly attributable to a changing sun, or whether, as the vast majority of climate scientists have shown, is due mostly to greenhouse gases generated by human civilization. The latter isn't simply a matter of personal preference; if you look at the data (PDF), it's clear that when the sun's output goes up, the temperature on Earth does too — but that for the past 50 years or so, the temperature has continued to climb even though the sun's brightness hasn't changed. That alone makes it clear that something else is driving up temperatures, and the "something" is almost certainly due to increasing concentrations of greenhouse gases. If the did start to brighten, of course, it could add to the warming, and if it started to dim significantly, it could offset the effect of human-induced warming.

Or so you'd think, anyway. But a new study in Nature (subs...


Get Ready for a La Nina Winter

Andrew Freedman

By Andrew Freedman

Last month we gave you a heads up that a La Nina event in the Pacific Ocean was strengthening and would help shape weather patterns for the next several months. Since then, it has become clearer that this La Nina is likely to remain as a moderate or even strong event, and may not abate until the spring of 2011. In other words — you’re going to be hearing a lot more about La Nina in the coming months.

In fact, you may start blaming it (not entirely unfairly, I might add) when you get soaked on your way home from work (more likely to happen this year in the Pacific Northwest and the Ohio Valley), or are told not to take long showers due to worsening drought conditions (more likely this year in the Southwest).

When present, La Nina, along with her better-known sibling, El Nino, acts as a principle architect of the planet’s weather patterns, especially during the fall and winter months. These events, which are part of a larger ocean and atmosphere cycle known to scientists as the “El Nino-Southern Oscillation” or ENSO, tend to occur about every two to seven years. They’re a key source of natural climate variability.

Sea surface temperature departures from average (in °C) from August 29 to September 25, 2010. Credit: NOAA/ESRL.

The chief hallmark of La Nina is a region of cooler-than-average water temperatures in the central to eastern equatorial Pacific Ocean, extending down along the northwest coast of South America. The cooler...