Revolution #28, December 26, 2005

Hurricanes, climate change and global warming

Part 1: Natural Climate Change

November 21 and 28 2005. A World to Win News Service. While the U.S. government has insisted that global warming doesn't exist, most scientists are convinced otherwise. Some researchers say global warming was a major factor in the deadly series of hurricanes (as the violent tropical storms or cyclones that hit the Americas are called) that struck the Caribbean, Central America and the U.S. recently. At the Montreal international summit on climate change , the first such meeting since the 1997 Kyoto summit, the U.S. continued to refuse to recognise the dangers or even the existence of global warming, which an attending UK scientist declared is as perilous to the future of humanity as weapons of mass destruction. Observers at the opening of the Montreal meeting of 190 countries had little hope that it would make real progress in achieving international agreements to limit greenhouse gas emissions, the main factor in the rapid rise in world temperatures. Even though the targets for reducing greenhouse gas emissions agreed to at Kyoto are criminally inadequate (the goal is to reduce emissions to 5 percent below the 1990 level by 2012), so far actual emissions have increased, not decreased even the European Union, which supported Kyoto, has failed to meet its target.

What is the link between global warming and tropical storms? What are the causes of global warming? To what extent is global warming caused by human activity, and what can be done about it? How dangerous is global warming? Why do the rulers of the U.S. and other major powers refuse to take serious action even as disaster stares mankind in the face? These questions are addressed in this article, which is being run in five parts.

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The international science journal Nature reported that possible links between hurricane formation and global warming are a contentious issue in climate policy. The depth of the divide between supporters and sceptics was already apparent in January, when U.S. meteorologist Chris Landsea resigned from the Intergovernmental Panel on Climate Change (IPCC) an organisation working with the United Nations Environmental Programme. Landsea was protesting against statements made by his panel colleague, Kevin Trenberth, who had argued for a link between global warming and storms in a press conference.

Nature wrote, "Trenberth's view is supported by the most recent and solid analysis of hurricane destructiveness over the past 30 years, by leading U.S. hurricane researcher Kerry Emanuel of the Massachusetts Institute of Technology in Cambridge, Massachusetts." Emanuel had concluded that "future warming may lead to an upward trend in tropical cyclone destructive potential, and... a substantial increase in hurricane-related losses in the 21st century."

Long before Hurricane Katrina, the IPCC stated in its 2001 assessment report: "There is some evidence that regional frequencies of tropical cyclones may change... There is also evidence that the peak intensity may increase by 5% to 10% and precipitation rates [rain] may increase by 20% to 30%. There is a need for much more work in this area to provide more robust results." In August 2005 the Gulf of Mexico was a striking 2-3°C warmer than it usually is at this time of year. Hurricanes are powered by the energy they draw from warm water. Katrina sucked so much heat energy from the Gulf that water temperatures dropped dramatically after the storm, in some regions from 30°C to 26°C.

Julian Heming, hurricane expert at the Met Office in Exeter, UK, says that a longer-term record is needed to establish a firm link between global warming and more powerful hurricanes. He said, "I would say that this paper corroborates the widely held view in the scientific community that whilst global warming may not be having any impact on the frequency of tropical cyclones or even the proportion which reach hurricane strength, it may have an impact on the small proportion of tropical cyclones which attain the highest strength (category 4 and 5)." This was the strength of Katrina.

While the link between global warming and hurricanes is emerging as a new controversial issue among scientists and much more research is required in this area, most scientists, to one degree or another, agree on certain facts about climate change and global warming that have emerged so far.

Natural climate changes

The Earth's atmosphere has dramatically changed since the planet formed 4.5 billion years ago. As scientists learn more about the atmosphere, they realise climate change is not a one-time, one-dimensional phenomenon. Major geological events have shaped the atmosphere that we live on today. The Earth's crust began to solidify about 4.0 billion years ago. About 3.5 billion years ago the Earth began to be inhabited by diverse organisms, first in the form of primitive single cells, with some of them then evolving to multi-cellular organisms. These and other forms of life have played a dynamic role in changing the atmosphere and the Earth as a whole.

An oxygen revolution began about 2.5 billion years ago. Primitive single-cell organisms use the Sun's energy to split water molecules (photosynthesis), producing the nutrients they need and releasing oxygen as a by-product. This release of oxygen changed the Earth's atmosphere profoundly. It made possible the evolution of aerobic [air-breathing] organisms other kinds of micro-organisms, plants and eventually animals that use oxygen to extract energy from food. This was not an easy or quick adaptation by any means. The process occurred during the almost 2 billion years that the primitive single-cell organisms had the whole Earth to themselves. After that, the interaction between plants that take in carbon dioxide and animals that take in oxygen and give off carbon dioxide was part of what has kept the proportions of these two gases in balance for millions of years.

Another event that changed the climate dramatically was the landmass movement known as Pangaea. About 250 million years ago, the Earth's land, formerly one single mass, began to split into northern (Laurasia) and southern (Gondwana) landmasses. Later on continental drift separated the landmass into the modern continents. India collided with Eurasia about 10 million years ago, forming the Himalayas, the tallest and youngest mountain range on Earth. These mountains drastically changed the Earth's atmosphere by capturing moisture and acting as a barrier against wind blowing from one continent to the other.

Also, external forces have influenced the atmosphere and the planet greatly. About 65 million years ago, an asteroid or comet struck what is now the Caribbean Sea near the Yucatan Peninsula of Mexico, creating an enormous horseshoe-shaped crater. The impact and its immediate effects killed most of the plants and animals in North America within minutes. A cloud of hot vapour and debris blocked out the Sun's rays, radically changing the atmosphere of the Earth. This caused the extinction of land animals and plants around the globe. The impact may have been one of a series of events that contributed to a global cooling trend at that time.

The Earth's history has been marked by alternating periods of relative cold when much of the northern and southern hemisphere is covered by glaciers, and relatively warmer periods when these glaciers retreat back toward the pole. The present interglacial period, called the Holocene, started about 10,000 years ago and is an example of the rare warm conditions that occur between each ice age. In less than 4,000 years global temperature increased by 6 C, the sea level rose by 120 metres, the amount of carbon in the atmosphere increased by a third, and atmospheric methane doubled. As the Earth warmed, in response to these changing climatic conditions human beings began to domesticate animals and grow crops. The first private property and exploitation also appeared and society became divided into classes with opposed interests. Humanity was to become an agent of climate change the likes of which the Earth had never seen in 4.5 billion years. Later, with the rise of capitalism and the explosive expansion of industry that it brought about starting around the beginning of the 19th century, human beings began to change their environment even more quickly and dramatically.

To be continued.

Next week: Man-made Climate Change

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