Global Warming to cost arctic countries? October 2, 2011.
A few years ago the CIA world factbook projected a surge in Russia's agricultural production in the warmer decades to come. Like many others, the CIA's analysts apparently assumed that in arctic countries warmer temperatures translated to a general expansion in arable land. Coupled with the arctic resources unlocked by thawing ice, in economic terms Canada, Russia and Greenland stood to gain far more than they lost under the new climatic regime. Now the National Roundtable on the Environment and the Economy, a government-backed Canadian initiative, has released a lengthy report that argues the opposite. In fact, the NRTEE projects that the death of forests, flooding of low-lying regions and spread of disease it associates with global warming could cost Canada some 2.5% of its GDP by 2075. Interestingly the NRTEE members include few academic representatives, among them no environmental historians, who might have corrected sentences like "climate change will lead to warmer summers and poorer air quality, resulting in increased deaths and illnesses." (17) Either way, as a historical climatologist I study the rise of the Dutch Republic - the world's first capitalist economy - during a period of pronounced climatic cooling and general European decline. Its counterintuitive growth - founded as much on trade and financial innovation as fishing or an evolving agriculture - might suggest that countries whose economies rely on natural resources could be more susceptible to periods of climatic transition.
Weather and tropical warfare: September 23, 2011.
As my colleague Sam White recently reported through the Climate History Network, a recent article in Nature reveals that from 1950 to 2004 conflict in the tropics was twice as common during El Niño years as it was in La Niña years. The authors - an interdisciplinary team from Columbia University's Earth Institute - even suggest that El Niño, which reduces rainfall and increases temperatures every 3-7 years, might account for a fifth of all global conflict. Their statistical work - while important - nevertheless reveals the importance of a truly interdisciplinary approach to the study of the relationship between climate, weather and human history. Long-since discarded by historical climatologists, the idea that any atmospheric event determines the course of human history continually threatens to not only marginalize the work of scholars examining climate's past, but to undermine projections of our future on a warmer planet. It is far more useful to conceive of any environmental structure as narrowing or expanding the range of human action, rather than causing those actions to happen.
The Antarctic ozone hole and a drier Australia: April 29, 2011.
Attempts to account for the Little Ice Age and other historical climatic fluctuations have too often focussed on monocausal explanations: a rise in volcanism, or example, or minima in solar radiation. A recent study in the journal Science has concluded that the ozone hole has altered the southern hemisphere's weather, especially in Australia, resulting in the southward movement of high-latitude atmospheric circulation. These high-altitude winds powerfully influence daily weather - for example, the coldest years of the Little Ice Age coincided with the blocking of usual high-altitude wind patterns across the northeastern Atlantic - and in Australia it seems that rainfall has moved south with the winds. Global warming and natural climatic cycles are also contributing to this phenomenon, revealing how diverse - if unequal - atmospheric and oceanic stimuli influence the world's changing climate. Now, as in the past, we cannot understand climatic fluctuations without considering a host of factors, both anthropogenic and otherwise. On a positive note, the Antarctic ozone hole should be repaired by 2060 at the latest.
Wintry weather and global warming: December 21, 2010.
One of the greatest misperceptions regarding climate change is the notion that the weather typically associated with a climatic shift is felt everywhere, every day, and works in gradual crescendos where each year is cooler or warmer than the next. Today that idea often has people questioning the reality of global warming during spells of cold weather, exhibited in the blizzards that swept through Europe and parts of the U.S. in the past week. In fact, however, climatic changes are often all about tipping points and violent events, associated weather phenomena vary from one region to the next, and overall trends of cooling or warming often mask sharp fluctuations from year to year. Meanwhile different stimuli with different climatic influences affect the world's climate on different timescales, in ways that can be mutually reinforcing or sharply contradictory. For example, the dominant engine driving global warming today is the anthropogenic emission of greenhouse gases, but volcanic activity or changes in solar radiation can tug at our planet's climate with less intensity, and usually over shorter timeframes. That would all be difficult enough to understand without recent studies suggesting reality might be even more complex. It turns out that cold, snowy winter weather in parts of the Northern Hemisphere might actually be a result of a warming Arctic climate. In the words of meteorologist Jeff Masters, "This pattern is kind of like leaving the refrigerator door ajar — the refrigerator warms up, but all the cold air spills out into the house."