This final chapter has comprehensively reviewed the evidence for contemporary anthropogenic climate change. The changing composition of the atmosphere (involving both greenhouse gases and aerosols) was discussed and its potential influence on greenhouse forcing and climate change examined. Despite the lack of unequivocal attribution for the enhanced greenhouse hypothesis, the evidence that mankind is changing the Earth's climate is beginning to mount.
If climate model projections prove to be even moderately accurate, global temperatures by the end of the next century will be higher than at any time during the last 120,000 years (see chapter 5). With such unprecedented climate change, impacts to all parts of the climate system are likely to be substantial. Failure to introduce some form of global greenhouse gas emission reduction strategy will merely extend the time frame of anthropogenic global warming that humanity may already be witnessing.