This page is based on a brief synopsis of the 2007 Fourth Assessment Report (AR4) by the Intergovernmental Panel on Climate Change (IPCC), as well as NCDC's own data resources.
Large-scale average climate conditions are determined by the general circulation of the atmosphere and oceans. But on smaller scales, local climates are influenced by many factors, such as terrain and vegetation, which can create ‘microclimates’ that differ significantly from their surroundings. One example is mid-latitude deserts. Most deserts are in the subtropics, but desert conditions also exist at certain mid-latitude locations – such as Death Valley, the driest place in the USA. Situated at about 36 degrees north in the Mojave Desert, the valley is cut off from the Pacific Ocean by three mountain ranges. Moisture flowing in from the Pacific is forced upwards, cooling and condensing into clouds.
The history of the scientific discovery of climate change began in the early 19th century when ice ages and other natural changes in paleoclimate were first suspected and the natural greenhouse effect first identified. In the late 19th century, scientists first argued that human emissions of greenhouse gases could change the climate , but the calculations were disputed. Many other theories of climate change were advanced, involving forces from volcanism to solar variation . In the 1960s, the warming effect of carbon dioxide gas became increasingly convincing, although some scientists also pointed out that human activities, in the form of atmospheric aerosols ( e.g., "pollution"), could have cooling effects as well.
George Perkins Marsh, 1801-1882, an American diplomat, is considered by some to be America's first environmentalist. Photograph: Library of Congress When we think of the birth of the conservation movement in the 19th century, the names that usually spring to mind are the likes of John Muir and Henry David Thoreau , men who wrote about the need to protect wilderness areas in an age when the notion of mankind's " manifest destiny " was all the rage. But a far less remembered American - a contemporary of Muir and Thoreau - can claim to be the person who first publicised the now largely unchallenged idea that humans can negatively influence the environment that supports them. George Perkins Marsh (1801-1882) certainly had a varied career.
Man and nature; or, Physical geography as modified by human action. By George P. Marsh...<blockquote>Table of Contents</blockquote>The Evolution of the Conservation Movement, 1850-1920 Man and nature; or, Physical geography as modified by human action. By George P. Marsh...
This diagram of the fast carbon cycle shows the movement of carbon between land, atmosphere, and oceans in billions of tons of carbon per year. Yellow numbers are natural fluxes, red are human contributions in billions of tons of carbon per year. White numbers indicate stored carbon. The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere , pedosphere , geosphere , hydrosphere , and atmosphere of the Earth.
Montage of some highly influential scientists from a variety of scientific fields. From left to right: Top row: Archimedes , Aristotle , Ibn al-Haytham , Leonardo da Vinci , Galileo Galilei , Antonie van Leeuwenhoek ; Second row: Isaac Newton , James Hutton , Antoine Lavoisier , John Dalton , Charles Darwin , Gregor Mendel ; Third row: Louis Pasteur , James Clerk Maxwell , Henri Poincaré , Sigmund Freud , Nikola Tesla , Max Planck ; Fourth row: Ernest Rutherford , Marie Curie , Albert Einstein , Niels Bohr , Erwin Schrödinger , Enrico Fermi ; Bottom row: Alan Turing , Richard Feynman , E. O. Wilson , Jane Goodall , Stephen Hawking , and Neil deGrasse Tyson