A changing climate: evidence and consequences

Abstract

Global climate is changing rapidly as a consequence of human activities increasing the concentration of ‘greenhouse gases’ in the atmosphere. The natural mix of these gases allows incoming solar radiation to warm the earth’s surface and prevents a proportion of the outgoing long-wave radiation from escaping to space. Without these radiative controls provided by our atmosphere, the earth would be about 30oC cooler and life as we know it would not have developed. Human activities, primarily burning of fossil fuels and land-use changes, have significantly increased the concentration of these atmospheric gases, with the consequence that more energy is trapped in the climate system, resulting in global warming. There are various lines of evidence to support the proposition that we are living in an era of rapid, human-induced changes in our global climate environment – theory, instrumental observations, paleoclimatic reconstructions and modelling.