Final answer:
The IPCC AR4 indicates that extreme weather events and changes in ecosystems are increasingly common due to human-caused climate change. The scientific consensus confirms this trend, acknowledging that anthropogenic actions are the primary drivers. These changes pose serious risks to natural habitats and species distribution, prompting calls for significant climate action.
Step-by-step explanation:
The Intergovernmental Panel on Climate Change (IPCC) Assessment Report 4 (AR4) reflects increasing concern that certain extreme events, such as severe weather, natural disasters, and changing ecosystems, are becoming more common as a result of human influences on climate. The phenomenon of climate change is linked to the warming trend primarily caused by human activities, leading to an increase in global temperature and shifts in rainfall and snowfall patterns. This has severe implications for the distribution and survival of species, as habitats become less hospitable and species must move to track their required climatic conditions. Additionally, human-made structures and landscape changes pose significant barriers to these necessary migrations.
Hazards related to climate change include the intensity and frequency of extreme weather events like abnormally heavy rainfall, prolonged droughts, desertification, and sea-level rise. Notable evidence of climate change's impact includes record-setting wildfires and shifts in marine species' distributions towards the poles. These changes are taking place within the context of a scientific consensus: global climate change is real and is largely driven by human actions. Despite internal disagreements on specific aspects of climate change, the overwhelming majority of scientists and reputable scientific agencies agree on these basic points.