Throughout historical times, Earth’s climate has changes several times. In the last half a million years or so there had been seven glacial advance retreat cycles, with the last one abruptly ending some seven thousand years ago. This also marks the start of the human civilization and the modern climatic era. Variation in the orbit of our planet brings about minor changes in the quantity of solar energy that we receive and was solely responsible for the climate changes till the last millennium.
The current climate trends is human induced and is proceeding at an alarming rate. Over the years scientist have been collecting and studying data about the climate of our planet across the globe using earth based satellites. Their studies have revealed an undisputed fact that scientific evidence for Earth’s climate warming exists.
In the middle of the last century, it was successfully demonstrated that gases like carbon monoxide, carbon dioxide, and several other greenhouse gases are efficient in trapping the heat. The scientific instruments that are used today are based on the ability of these gases to transfer the infrared energy through Earth’s atmosphere.
The ice core samples collected from expedition to Antarctica, arctic region in the initial exploration years and from the permanent bases of today in these regions along with Greenland and mountain glaciers around the tropics have shown how the Earth’s atmosphere responds to suns energy output. Also it responds to Earth’s orbit and greenhouse gas levels in the atmosphere.
There are more compelling evidence suggesting climate change and global warming is for real. The following are a few of them.
- Rise in Global Temperatures – Surface temperature profiling carried out by NASA have shown that Earth has become warmer since 1880 with major warming happening since the 1970s. 1981 to 2001 were the warmest twenty years of the century. And of these 10 were the warmest years.
- Warming of Oceans Since 1969 – The oceans world over have received and absorbed much of the heat. The top 700 to 800 feet of ocean have warmed by 0.302 degrees.
- Shrinking of Polar Ice Sheets – Between 2005 and 2006 Greenland and Antarctica together lost 300 to 400 cubic kilometers of their ice sheets. Exposing some of the land mass that was no visible before. Also access to North Pole has now become easier as ice breakers can easily reach the polar region.
- Rise in global sea levels – Since last century the sea levels across the oceans around the world have risen about 6.7 inches.
- Retreat of major glaciers of the world – Major glaciers around the world have retreated at an alarming rate and it includes some prominent glaciers located in the Alps, Rockies, Alaska, Himalayas, Andes, Africa.