The 2000 year cooling cycle, often called the Little Ice Age, ended in 1850 when the advancing Industrial Revolution really began human warming. The Little Ice Age was caused by a wobble in the Earth's axis of rotation which increased the Earth's distance from the Sun during the Arctic summer.
“Recently there have been temperatures that are far below normal in England and even Norway as well as in the eastern United States but at the same time there were higher than normal temperatures on the West Coast of the US. But this is all weather— not climate. Then, of course, natural phenomena can affect the weather.
“The volcanic eruption in Iceland in 2010 caused parts of the world to cool because the volcanic dust blocked out some of the sun’s rays. But these changes are not related to climate change unless they persist for many years and affect the whole planet.
“In spite of the local ups and downs there is no doubt that global warming is speeding up. It is very likely that the upward trend in hot extremes and heat waves will continue. The duration and intensity of droughts have increased over greater areas since the 1970s, particularly in the tropics and subtropics. The Sahel area below the Sahara, the Mediterranean, southern Africa and parts of southern Asia have already become drier during the 20th century. (20) We have suffered from droughts here in California too, as you well know.
“It is particularly notable in the Arctic where ice is melting and where the exposed
ground, which once reflected light back out to the atmosphere when it was covered with ice, now absorbs the heat. And these ice sheets, particularly the West Antarctic and the Greenland ice sheets, are melting faster than we thought. This should raise the sea level faster than expected, possibly as much as four feet in the century.”
“The records of Arctic temperatures for the last 2000 years show that the first decade
of this century was the warmest ever. And each year gets warmer. Without the human
activity, the Arctic areas would have been about 1.4 degrees Celsius cooler than they have been recently. During the 20th century Arctic temperatures increased about three times
faster than the rest of the Northern Hemisphere.”
“I remember reading about 15 years ago that all of the 15 warmest years on record
had come in the previous 20 years. And it wasn’t just the thermometer talking. Hurricanes were getting stronger. We know that winter ice coverage of the Great Lakes has been reducing almost 1% per year over the last few decades. The Arctic and Antarctic ice caps are melting much faster than normal.”
“Temperature records began to be kept in 1870. In recent years temperature collection has become more sophisticated. In addition to the worldwide temperature collecting stations, which number over a thousand, there are data on surface sea temperatures from satellites and there are the Antarctic research station measurements. These are analyzed by the Goddard Institute for Space Studies for NASA. Each decade since the 1980s has become warmer by about one-fifth of a degree Celsius. If we look back at the first decade of this century we find that 2005 was the warmest year with the following two years being tied for the second warmest year of all-time. If we look at the hemispheric differences, while 2005 was the warmest year on record for the northern hemisphere, 2009 was the warmest for the southern hemisphere. In the north, in 2008, there was a cooling trend due to a strong La Niña effect
over the Pacific Ocean, but as it dissipated temperatures in the north regained their upward momentum.
“Pressure differences can also make a difference in the weather in large parts of the world. In 2009 a high-pressure system in the Arctic disrupted normal east-west flow of the jet stream causing cold air from the Arctic to move south in North America. This cooled North America but warmed the Arctic.
“American skeptics often cite cooler temperatures in some of their states as evidence of global cooling. The 48 contiguous states of the US account for only one and a half percent of the world’s surface, so extrapolating the world’s temperature from yesterday’s cold spell in Chicago misses the point entirely. Also criticizing the possible inaccuracies of tree ring dating does not change the fact that over the last 150 years there has been significant warming. (20a)
“Being familiar with the research would help the skeptics understand that most of the warmest years in history have occurred in the last 30 years. If the skeptics want to criticize the measurements of NASA perhaps they need to develop a program that is as
extensive as that of NASA’s. If they want to criticize temperature reports from the 1000+ monitoring stations perhaps they need to set up their own 1,000+ stations around the world. It’s just not enough to take a few bits of minor information and criticize the major findings which are accepted by over 95% of the scientists who study the phenomena.
Having a doctor or lawyer or a weatherman criticize the huge amount of evidence without having an equally huge amount of evidence to counter it is anti-intellectual. But as a political tactic it may have a delaying action on a government making a major start on saving the planet.”