Climate change includes both the global warming driven by human emissions of greenhouse gases, and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century the rate of human impact on Earth's climate system and its global scale have been unprecedented.
Many of these effects are already observed at the current level of warming, which is about 1.1 °C (2.0 °F). The Intergovernmental Panel on Climate Change (IPCC) has issued a series of reports that project significant increases in these impacts as warming continues to 1.5 °C (2.7 °F) and beyond. Under the Paris Agreement, nations agreed to keep warming "well under 2.0 °C (3.6 °F)" by reducing greenhouse gas emissions. However, under those pledges, global warming would reach about 2.8 °C (5.0 °F) by the end of the century, and current policies will result in about 3.0 °C (5.4 °F) of warming. Limiting warming to 1.5 °C (2.7 °F) would require halving emissions by 2030, then reaching near-zero levels by 2050. (Full article...)
The runaway greenhouse effect is often formulated with water vapor as the condensable species. In this case the water vapor reaches the stratosphere and escapes into space via hydrodynamic escape, resulting in a desiccated planet. This may have happened in the early history of Venus. (Full article...)
Global vegetation – Food, fuel and shelter. Vegetation is one of the most important requirements for human populations around the world. Satellites monitor how "green" different parts of the planet are and how that greenness changes over time. These observations help scientists understand the influence of natural cycles, such as drought and pest outbreaks, on vegetation, as well as human influences, such as land-clearing and global warming.
The following are images from various climate-related articles on Wikipedia.
Biosphere CO 2 flux in the northern hemisphere summer (NOAA Carbon Tracker)
Energy flows between space, the atmosphere, and Earth's surface. Current greenhouse gas levels are causing a radiative imbalance of about 0.9 W/m2.
A pictogram of the greenhouse effect
Graph of CO2 (green), reconstructed temperature (blue) and dust (red) from the Vostok ice core for the past 420,000 years
Frequency of occurrence (vertical axis) of local June–July–August temperature anomalies (relative to 1951–1980 mean) for Northern Hemisphere land in units of local standard deviation (horizontal axis). According to Hansen et al. (2012), the distribution of anomalies has shifted to the right as a consequence of global warming, meaning that unusually hot summers have become more common. This is analogous to the rolling of a dice: cool summers now cover only half of one side of a six-sided die, white covers one side, red covers four sides, and an extremely hot (red-brown) anomaly covers half of one side.
Carbon Dioxide observations from 2005 to 2014 showing the seasonal variations and the difference between northern and southern hemispheres
Atmospheric gases only absorb some wavelengths of energy but are transparent to others. The absorption patterns of water vapor (blue peaks) and carbon dioxide (pink peaks) overlap in some wavelengths. Carbon dioxide is not as strong a greenhouse gas as water vapor, but it absorbs energy in longer wavelengths (12–15 micrometers) that water vapor does not, partially closing the "window" through which heat radiated by the surface would normally escape to space. (Illustration NASA, Robert Rohde)
CO 2 concentrations over the last 800,000 years
Modeled simulation of the effect of various factors (including GHGs, Solar irradiance) singly and in combination, showing in particular that solar activity produces a small and nearly uniform warming, unlike what is observed.
Contribution of natural factors and human activities to radiative forcing (RF) of climate change. RF values are for year 2011, relative to pre-industrial (1750).
Mean temperature anomalies during the period 1965 to 1975 with respect to the average temperatures from 1937 to 1946. This dataset was not available at the time.
This diagram of the fast carbon cycle shows the movement of carbon between land, atmosphere, and oceans in billions of metric tons of carbon per year. Yellow numbers are natural fluxes, red are human contributions in billions of metric tons of carbon per year. White numbers indicate stored carbon.
Probability density function (PDF) of fraction of surface temperature trends since 1950 attributable to human activity, based on IPCC AR5 10.5
The Keeling Curve shows the long-term increase of atmospheric carbon dioxide (CO 2) concentrations from 1958–2018. Monthly CO 2 measurements display seasonal oscillations in an upward trend. Each year's maximum occurs during the Northern Hemisphere's late spring.
Concentration of atmospheric CO 2 over the last 40,000 years, from the Last Glacial Maximum to the present day. The current rate of increase is much higher than at any point during the last deglaciation.
Biosphere CO 2 flux in the northern hemisphere winter (NOAA Carbon Tracker)
Quantitative analysis: Energy flows between space, the atmosphere, and Earth's surface, with greenhouse gases in the atmosphere capturing a substantial portion of the heat reflected from the earth's surface.
CO 2 sources and sinks since 1880. While there is little debate that excess carbon dioxide in the industrial era has mostly come from burning fossil fuels, the future strength of land and ocean carbon sinks is an area of study.
Solar irradiance (yellow) plotted together with temperature (red) over 1880 to 2018.
In 1896 Svante Arrhenius calculated the effect of a doubling atmospheric carbon dioxide to be an increase in surface temperatures of 5–6 degrees Celsius.
Air-sea exchange of CO 2
Correspondence between temperature and atmospheric CO 2 during the last 800,000 years
Photosynthesis changes sunlight into chemical energy, splits water to liberate O2, and fixes CO2 into sugar.
False-color image of smoke and ozone pollution from Indonesian fires, 1997
T. C. Chamberlin
Top panel: Observed global average temperature change (1870— ). Bottom panel: Data from the Fourth National Climate Assessment is merged for display on the same scale to emphasize relative strengths of forces affecting temperature change. Human-caused forces have increasingly dominated.
Global fossil carbon emissions 1800–2014
Observed temperature from NASA vs the 1850–1900 average used by the IPCC as a pre-industrial baseline. The primary driver for increased global temperatures in the industrial era is human activity, with natural forces adding variability.
Global average temperatures show that the Medieval Warm Period was not a planet-wide phenomenon, and that the Little Ice Age was not a distinct planet-wide time period but rather the end of a long temperature decline that preceded recent global warming.
Erratics, boulders deposited by glaciers far from any existing glaciers, led geologists to the conclusion that climate had changed in the past.
... Arctic haze contributes to global warming, raising temperatures by up to 5.4°F (3°C) during the arctic winter? A major distinguishing factor of Arctic haze is the ability of its chemical ingredients to persist in the atmosphere for an extended period of time compared to other pollutants.
A view of Sand Mountain campground from the side of Sand Mountain at Little Sahara Recreation Area in Utah. The Little Sahara sand dunes are remnants of a large river delta formed by the Sevier River from about 12,500 to 20,000 years ago. The river emptied into ancient Lake Bonneville near the present day mouth of Leamington Canyon. After Lake Bonneville receded, winds transported the sand from the river delta to the current location. The dunes are still moving 5 to 9 feet (1.5 to 3 m) per year. The area is home to typical Great Basin desert wildlife including mule deer, pronghorn antelope, snakes, lizards and birds of prey. Great horned owls make their home among juniper trees in the Rockwell Natural Area.