History of Climate change in Timeline

Climate change encompasses both the ongoing rise in global average temperature (global warming) and its broader impacts on Earth's climate system. Modern climate change is primarily driven by human activities, particularly the burning of fossil fuels since the Industrial Revolution. These activities, along with deforestation and certain agricultural and industrial practices, release greenhouse gases into the atmosphere. These gases trap heat, causing a warming effect. The concentration of carbon dioxide, the main greenhouse gas, is now roughly 50% higher than pre-industrial levels, reaching levels unseen in millions of years.

1900: Pre-industrial baseline

The decade between 2014 and 2023 warmed to an average 1.19 °C compared to the pre-industrial baseline between 1850 and 1900.

1938: Guy Stewart Callendar Publishes Evidence of Warming and Rising CO2 Levels

Beginning in 1938, Guy Stewart Callendar presented evidence indicating that the climate was warming and CO2 levels were increasing. However, his calculations were met with skepticism and objections.

1961: Observation of global dimming

From 1961 to 1990, a gradual reduction in the amount of sunlight reaching the Earth's surface was observed. This phenomenon is known as global dimming, and is primarily attributed to sulfate aerosols produced by the combustion of fossil fuels.

1970: Marked increase in temperature

After 1970, the increasing accumulation of greenhouse gases and controls on sulfur pollution led to a marked increase in temperature.

1970: Thermal energy increase in the global climate system

Since at least 1970, thermal energy in the global climate system has grown, with over 90% of this extra energy being stored in the ocean.

1975: Early Usage of 'Global Warming'

The term "global warming" was used as early as 1975 to describe the increasing temperature of the earth.

1979: National Research Council's Charney Report Supports Climate Models

In 1979, the National Research Council's Charney Report was published, supporting the accuracy of climate models that forecast significant warming.

1980: Increase in monsoonal precipitation

Since 1980, monsoonal precipitation over the Northern Hemisphere has increased.

1988: James Hansen's Testimony Before US Senate Committee

In 1988, James Hansen testified before a US Senate committee, publicly presenting the human causation of observed global warming and the dangers of unmitigated warming.

1988: James Hansen's Testimony

In 1988, NASA climate scientist James Hansen used the term "global warming" in his testimony in the U.S. Senate, leading to its increased popularity.

1990: Observation of global dimming

1990: Underestimation of sea level rise

Sea level rise since 1990 was underestimated in older models, but more recent models agree well with observations.

1998: Start of global warming hiatus

From 1998 to 2013, negative phases of Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) caused a short slower period of warming called the "global warming hiatus".

2000: Sea level rise

The result of long-term effects of climate change on oceans is an estimated total sea level rise of 2.3 metres per degree Celsius (4.2 ft/°F) after 2000 years.

2001: Deforestation for agriculture

Between 2001 and 2018, 27% of deforestation was from permanent clearing to enable agricultural expansion for crops and livestock.

2013: End of global warming hiatus

From 1998 to 2013, negative phases of Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) caused a short slower period of warming called the "global warming hiatus".

2014: Increase in sea level rise

Between 2014 and 2023, sea level rise has increased over time, reaching 4.8 cm per decade.

2014: Warm decade

The decade between 2014 and 2023 warmed to an average 1.19 °C compared to the pre-industrial baseline between 1850 and 1900.

2015: Paris Agreement

In 2015, nations collectively agreed under the Paris Agreement to keep global warming "well under 2 °C". However, current pledges under the agreement are insufficient to meet this goal.

2015: Paris Climate Accord

In 2015, the Paris Climate Accord was created. According to the UN's International Court of Justice issued on July 23, 2025, nations must implement their commitments in the Paris Climate Accord.

2017: National Climate Assessment

The 2017 United States-published National Climate Assessment notes that "climate models may still be underestimating or missing relevant feedback processes".

2018: Deforestation for agriculture

Between 2001 and 2018, 27% of deforestation was from permanent clearing to enable agricultural expansion for crops and livestock.

2019: Scientific Agreement on Climate Change Reaches Over 99%

As of 2019, agreement in recent scientific literature reached over 99% regarding the consensus that the climate is warming and that this is caused by human activities.

2019: Global human-caused greenhouse gas emissions

In 2019, global human-caused greenhouse gas emissions were equivalent to 59 billion tonnes of CO2. 75% of these emissions was CO2, 18% was methane, 4% was nitrous oxide, and 2% was fluorinated gases.

2020: Effect of decreasing sulfur content of fuel oil for ships

The effect of decreasing sulfur content of fuel oil for ships since 2020 is estimated to cause an additional 0.05 °C increase in global mean temperature by 2050.

2021: IPCC Sixth Assessment Report

In 2021, the IPCC Sixth Assessment Report included projections that by 2100, global warming is very likely to reach 1.0–1.8 °C under a scenario with very low emissions of greenhouse gases, 2.1–3.5 °C under an intermediate emissions scenario, or 3.3–5.7 °C under a very high emissions scenario.

2021: IPCC Assessment Report States Climate Change is 'Unequivocal'

The 2021 IPCC Assessment Report stated that it is "unequivocal" that climate change is caused by humans.

2022: Increase in greenhouse gas concentrations

In 2022, the concentrations of CO2 and methane had increased by about 50% and 164%, respectively, since 1750, surpassing levels not seen in millions of years.

2023: Carbon budget estimation

According to UNEP, global warming can be kept below 2.0 °C with a 50% chance if emissions after 2023 do not exceed 900 gigatonnes of CO2.

2023: Increase in sea level rise

Between 2014 and 2023, sea level rise has increased over time, reaching 4.8 cm per decade.

2023: Warm decade

The decade between 2014 and 2023 warmed to an average 1.19 °C compared to the pre-industrial baseline between 1850 and 1900.

2024: Warmest year on record

In 2024, the Earth experienced its warmest year on record, with temperatures reaching +1.60 °C (2.88 °F) above pre-industrial levels since regular tracking began in 1850.

2024: Temperature well above recent average

In 2024, the temperature was well above the recent average at more than +1.5 °C.

2024: Probability of exceeding +1.5 °C

The World Meteorological Organization estimates there is almost a 50% chance of the five-year average global temperature exceeding +1.5 °C between 2024 and 2028.

July 2025: UN's International Court of Justice Issues Advisory Opinion

On July 23, 2025, the UN's International Court of Justice issued an advisory opinion, stating that nations must act to prevent climate change and can be sued by other states if they fail to meet this obligation. This includes adhering to commitments made in international agreements like the 2015 Paris Climate Accord.

2025: FAO Report on Land and Water Resources

In 2025, the Food and Agriculture Organization of the United Nations (FAO) published "The State of the World’s Land and Water Resources for Food and Agriculture 2025".

2028: Probability of exceeding +1.5 °C

The World Meteorological Organization estimates there is almost a 50% chance of the five-year average global temperature exceeding +1.5 °C between 2024 and 2028.

2050: Projected deaths due to climate change

According to the World Economic Forum, 14.5 million more deaths are expected due to climate change by 2050.

2050: Projected deaths from malnutrition due to drought

According to the World Economic Forum, an increase in drought in certain regions could cause 3.2 million deaths from malnutrition by 2050 and stunting in children.