Terminology and Historical Context:
– Before the 1980s, ‘inadvertent climate modification’ was used, which transitioned to ‘global warming’ and ‘climate change.’
– ‘Global warming’ refers to surface warming, while ‘climate change’ encompasses broader effects.
– James Hansen’s 1988 testimony popularized ‘global warming.’
– Climate has varied historically, with sea levels and temperatures fluctuating significantly.
– Historical warming and cooling patterns varied across regions.
Global Temperature Rise and Human Influence:
– Global surface temperature has risen by almost 1.5°C since the Industrial Revolution.
– Climate change, primarily due to burning fossil fuels, has led to increased temperatures.
– Greenhouse gases like carbon dioxide have increased by around 50%.
– Human activities significantly contribute to climate change through greenhouse gas emissions.
– Climate change has resulted in more intense storms, heatwaves, and wildfires.
Efforts to Combat Climate Change and Future Projections:
– Limiting warming to 1.5°C requires halving emissions by 2030 and achieving net-zero emissions by 2050.
– Phasing out fossil fuels and transitioning to clean energy sources is crucial.
– The Paris Agreement aims to keep global warming below 2°C, but current pledges may lead to 2.7°C warming by 2100.
– Global temperatures are projected to continue rising, with various scenarios based on emissions.
– Proactive measures and emission reductions are essential to limit global warming.
Impact of Climate Change and Feedback Mechanisms:
– Climate change affects oceans, ice, weather patterns, and ecosystems.
– Different warming levels can trigger tipping points in the climate system.
– Feedback mechanisms like increased moisture in warmer air and reduced Arctic snow cover impact climate.
– Earth’s ability to absorb carbon depends on emission levels and future climate changes.
– Positive feedback loops can intensify climate change impacts over time.
Sources of Carbon Emissions and Long-Term Carbon Removal:
– Fossil fuels, deforestation, methane emissions, and industrial processes are major sources of CO2.
– Long-term carbon removal processes involve natural sinks like land surfaces and oceans.
– Earth’s ability to store and absorb CO2 plays a crucial role in the carbon cycle.
– Land and ocean processes absorb a significant percentage of global CO2 emissions.
– Efforts to reduce emissions and enhance carbon removal are essential for mitigating climate change.
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global average temperature is primarily caused by humans burning fossil fuels since the Industrial Revolution. Fossil fuel use, deforestation, and some agricultural and industrial practices add to greenhouse gases. These gases absorb some of the heat that the Earth radiates after it warms from sunlight, warming the lower atmosphere. Carbon dioxide, the primary greenhouse gas driving global warming, has grown by about 50% and is at levels unseen for millions of years.
Climate change has an increasingly large impact on the environment. Deserts are expanding, while heat waves and wildfires are becoming more common. Amplified warming in the Arctic has contributed to thawing permafrost, retreat of glaciers and sea ice decline. Higher temperatures are also causing more intense storms, droughts, and other weather extremes. Rapid environmental change in mountains, coral reefs, and the Arctic is forcing many species to relocate or become extinct. Even if efforts to minimise future warming are successful, some effects will continue for centuries. These include ocean heating, ocean acidification and sea level rise.
Climate change threatens people with increased flooding, extreme heat, increased food and water scarcity, more disease, and economic loss. Human migration and conflict can also be a result. The World Health Organization (WHO) calls climate change the greatest threat to global health in the 21st century. Societies and ecosystems will experience more severe risks without action to limit warming. Adapting to climate change through efforts like flood control measures or drought-resistant crops partially reduces climate change risks, although some limits to adaptation have already been reached. Poorer communities are responsible for a small share of global emissions, yet have the least ability to adapt and are most vulnerable to climate change.
![A dry lakebed in California, which is experiencing its worst megadrought in 1,200 years.[18]](https://en.wikipedia.org/wiki/File:California_Drought_Dry_Lakebed_2009.jpg)
Many climate change impacts have been felt in recent years, with 2023 the warmest on record at +1.48 °C (2.66 °F) since regular tracking began in 1850. Additional warming will increase these impacts and can trigger tipping points, such as melting all of the Greenland ice sheet. Under the 2015 Paris Agreement, nations collectively agreed to keep warming "well under 2 °C". However, with pledges made under the Agreement, global warming would still reach about 2.7 °C (4.9 °F) by the end of the century. Limiting warming to 1.5 °C will require halving emissions by 2030 and achieving net-zero emissions by 2050.
Fossil fuel use can be phased out by conserving energy and switching to energy sources that do not produce significant carbon pollution. These energy sources include wind, solar, hydro, and nuclear power. Cleanly generated electricity can replace fossil fuels for powering transportation, heating buildings, and running industrial processes. Carbon can also be removed from the atmosphere, for instance by increasing forest cover and farming with methods that capture carbon in soil.