A brief history of climate change:
who knew what, when, and what they did (and still are doing)
Image: Patrick Hendry
We’ve known about greenhouse gases and the impact of carbon dioxide (CO2) on the climate for a very, very long time:
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50 AD
[CO2 in the atmosphere: ~270 ppm]
Knowing how heat can be trapped in an atmosphere, the first known greenhouse, a specularium, was built for the Roman Emperor Tiberius.
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1820
[CO2 in the atmosphere: 284 ppm]
Mathematician and physicist Joseph Fourier put forward the idea that Earth’s atmosphere might act as an insulator by retaining some radiation from the sun.
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1856
[CO2 in the atmosphere: 285.6 ppm]
Eunice Foote’s research on how increasing ‘carbonic acid’—carbon dioxide—in the atmosphere would cause warming, was presented at the American Association for the Advancement of Science (AAAS) (Fig. 1). Because women were not allowed to present their work, her paper was read by Joseph Henry, the first secretary of the Smithsonian Institution. It was the only paper by a women presented in the first 10 years of annual AAAS meetings and was published as a short article in the American Journal of Science and Arts. It was and remains largely overlooked in the history of climate change research.
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1859
[CO2 in the atmosphere: 286.1 ppm]
Independently of Foote, physicist John Tyndall’s built on Fourier’s idea by describing the physics and chemistry of how greenhouse gases trap heat in the atmosphere (see: ‘What causes climate change‘ this website).
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1896
[CO2 in the atmosphere: 294.9 ppm]
Swedish scientist and Nobel Prize winner Svante Arrhenius realised that burning fossil fuels adds carbon dioxide to the atmosphere, which may eventually cause global warming.
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1912
[CO2 in the atmosphere: 300.4 ppm]
The Rodney and Otamatea Times (NZ) reported that burning coal will affect the climate: reported that burning coal will affect the climate:
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1954
[CO2 in the atmosphere: 312.4 ppm]
Scientists funded by oil companies to research air pollution warn that burning fossil fuels is increasing atmospheric CO2 and may ‘ultimately prove of considerable significance to civilization‘:
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1958
[CO2 in the atmosphere: 314.9 ppm]
The scientists in the above report started tracking CO2 concentrations at Mauna Loa observatory in Hawaii.
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1968
[CO2 in the atmosphere: 323.7 ppm]
Stanford Reseach Institute (SRI) scientists Elmer Robinson and R.C. Robbins produced a Final Report to the American Petroleum Institute (API) on SRI’s research in the sources, abundance, and fate of gaseous pollutants in the atmosphere. They reserved their starkest warnings to industry leaders for carbon dioxide. Robinson observed that, among the pollutants reviewed, that carbon dioxide “is the only air pollutant which has been proven to be global importance to man’s environment on the basis of a long period of scientific investigation.” Summarizing the findings of the President’s Science Advisory Council, Robinson noted that CO2 emissions from fossil fuels were outstripping the natural CO2 removal processes that keep the atmosphere in equilibrium.
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1982
[CO2 in the atmosphere: 342 ppm]
Scientists at Mobil-Exxon, one of the world’s largest companies producing fossil fuels, unequivocally stated: “The effects will indeed be catastrophic (at least for a substantial fraction of the world’s population).” Their predictions were remarkably accurate. The red line in Figure 3 shows that they expected it could reach 420ppm and 1.2°C warming by the year 2020. ExxonMobil then spend millions of dollars over the following decades on public and political campaigns to denounce climate change as a hoax, as they feared it would damage their profits.
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1988
[CO2 in the atmosphere: 351 ppm]
June: NASA scientist James Hansen testifies before the U.S. Senate: “The greenhouse effect has been detected, and is changing our climate now.“
December: The World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) establish the Intergovernmental Panel on Climate Change (IPCC) to provide policymakers with regular scientific assessments on the current state of knowledge about climate change.
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1990
[CO2 in the atmosphere: 354 ppm]
The First IPCC Assessment Report (FAR) underlined the importance of climate change as a challenge with global consequences that requires international cooperation. It plays a decisive role in creating the UNFCCC, the key international treaty to reduce global warming and cope with the consequences of climate change.
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1994
[CO2 in the atmosphere: 358 ppm]
Michael Mann and other scientists publish a paper with a graph that shows how temperatures were slowly cooling for the past thousand years, and then suddenly started rising during the Industrial revolution, when we started burning fossil fuels (oil and coil) to power industry. Climatologist Jerry Mahlman describes the graph as a ‘hockey stick’.
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1995
[CO2 in the atmosphere: 360 ppm]
The IPCC Second Assessment Report (SAR) provides important material for governments to use in the run-up to adoption of the Kyoto Protocol in 1997.
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1997
[CO2 in the atmosphere: 364 ppm]
The Kyoto Protocol to reduce greenhouse gas emissions is adopted on 11 December. Only developed countries are expected reduce emissions because they are the largest emitters, however the agreement doesn’t come into effect because of complications.
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1998
[CO2 in the atmosphere 367 ppm]
Michael Mann’s ‘Hockey Stick’ graph leads to a decades-long legal harassment from US fossil-fuel interests to discredit climate science. Fossil fuels companies including Exxon and Chevron spend millions of dollars on a global marketing campaign to debunk climate change as a myth.
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2001
[CO2 in the atmosphere 372 ppm]
The IPCC Third Assessment Report (TAR) is released. This focusses attention on the impacts of climate change and the need for adaptation.
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2005
[CO2 in the atmosphere 379 ppm]
The 1997 Kyoto Protocol enters into force: developed nations agree to reduce greenhouse gas emissions to limit climate change.
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2007
[CO2 in the atmosphere: 384 ppm]
The IPCC Fourth Assessment Report (AR4) lays the ground work for a post-Kyoto agreement, focusing on limiting warming to 2°C.
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2013-2014
[CO2 in the atmosphere 399 ppm]
The IPCC The Fifth Assessment Report (AR5) was finalized between 2013 and 2014. It provides the scientific input into the Paris Agreement.
By late 2014, the amount of carbon dioxide in the atmosphere passes 400ppm for the first time in almost 3 million years.
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2015
[CO2 in the atmosphere: 401 ppm]
Climate scientists have calculated that a safe atmospheric CO2 limit is 350ppm, which translates to 1°C of warming above pre-industrial levels.
The Paris Climate Conference resulted in 197 countries resolving to limit the planet’s average temperature to 1.5°C above pre-industrial levels. This would give us a 67% probability of avoiding irreversible catastrophic impacts. The calculations did not take into account climate tipping points already underway.
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2019
[CO2 in the atmosphere: 410 ppm]
The New Zealand Climate Change Response (Zero Carbon) Amendment Act 2019 is passed.
The United Nations GAP report shows that the world is not reducing emissions fast enough to keep temperatures under 1.5°C , or even 2°C. Instead, we are heading for more than 3°C.
The IPCC releases three Special Reports:
- 2019 Refinement; update to the 2006 IPCC Guidelines on National Greenhouse Gas Inventories.
- Special Report on Climate Change and Land (SRCCL)
- Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC).
Global fossil fuel energy giant Chevron is sued:
This activity [by Chevron] has released an immense amount of greenhouse gas into the Earth’s atmosphere, changing its climate and leading to all kinds of displacement, death (extinctions, even), and destruction. What is more, defendants understood the consequences of their activity decades ago, when transitioning from fossil fuels to renewable sources of energy would have saved a world of trouble. But instead of sounding the alarm, defendants went out of their way to becloud the emerging scientific consensus and further delay changes—however existentially necessary—that would in any way interfere with their multibillion-dollar profits. All while quietly readying their capital for the coming fallout. – William E. Smith, Chief Judge, State of Rhode Is vs Chevron Corp.
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2020
[CO2 in the atmosphere: 415 ppm]
The Ministry for the Environment tells Climate Change Minister James Shaw that New Zealand’s Paris Agreement target is inconsistent with the Government’s goal of keeping the average temperature increase to within 1.5°C. Simply put, we are emitting too many greenhouse gases to keep climate change under dangerous levels.
December: Emissions Gap Report – we are on track for more than 3°C warming
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2021
[CO2 in the atmosphere: 417 ppm]
The New Zealand Climate Commission Climate Change Commission’s first package of advice to government to help Aotearoa transition to a thriving, climate-resilient and low emissions future.
A staggering 5-billion-tonne gap in the carbon budget is identified: some countries are under-accounting how much they are emitting and/or over-accounting how much they are drawing down through forestry.
September: New Zealand Government announces it’s delaying any plans until May 2022
October: New Zealand Government puts out (yet another) discussion document, having done virtually no work on the Climate Commission’s proposals.
November: COP26 fails; temperatures are now on track to reach 2.7 – 3.6°C
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2022
February: The IPCC releases the Sixth Assessment Report: Impacts, Adaptation and Vulnerability.
I’ve seen many scientific reports in my time but nothing like this. Today’s IPCC report is an atlas of human suffering and the damning indictment of failed climate leadership. This report reveals that all people on the planet are getting clobbered by climate change. Nearly half of humanity is living in the danger zone. Now. Many ecosystems are at the point of no return. Now. And unchecked carbon pollution is forcing the globe’s most vulnerable on a frog march to destruction. Now. The facts are undeniable. This abdication of leadership is criminal. – António Guterres, Secretary-General of the United Nations.
February: Exxon, Mobil and a dozen other fossil fuel companies start oil and gas projects that will produce greenhouse gases equivalent to a decade of CO2 emissions from China, the world’s biggest polluter, or about 18 years of current global CO2 emissions. About 60% of these have already started pumping. The dozen biggest companies are on track to spend $103m a dayfor the rest of the decade.
May: NZ Government releases Emissions Reductions Targets and Emissions Reduction Plan.
August: NZ Government releases Climate Adaptation Plan.
November: State of the Cryosphere Report: the world’s climate is destablising due to catastrophic melting of the cryosphere. High sea level rises are now locked in, and:
The speed of today’s acidification is occurring far too quickly to allow species of today to evolve and survive. Both polar oceans already appear to be nearing a critical ocean acidification chemical threshold. It will take some 50,000–70,000 years to bring acidification and its impacts back to pre-industrial levels. The only way to slow and eventually halt the acidification process is through rapid CO2 emissions reductions and future carbon dioxide removal. (pp43-44)
November: COP27 – emissions are increasing, not decreasing. Governments are unwilling to take action to meet even their weak 2021 commitments; several countries are now increasing fossil-fuel production.
December: NZ Government capitulates to the farming sector on greenhouse gas emissions, and ignores Climate Commission advice to increase the cost of carbon emissions.
- Funding cut backs for NIWA means that the capacity to model future climate change is now reduced:
Olaf Morgenstern finished up after 15 years at NIWA last Friday – one of four experts culled from a 10-person climate modelling team… ’We would be truly in dire straits if everybody else followed New Zealand’s commercial ideology because we’d be sleepwalking into a climate disaster.’ – Radio NZ 23 July 2024
- In the US: Far-right industry allies with ties to Chevron have mounted an unprecedented pressure campaign calling on the Supreme Court to stop a potentially historic climate deception lawsuit against oil majors from going to trial. Republican attorneys general are separately urging the Supreme Court to throw out similar climate fraud lawsuits from five states. – De Smog Blog 24 July, 2024
- ~3.3 billion people—40% of the Earth’s population—experienced their warmest year ever.
- The New Zealand Government gave itself the power to exempt parts of the country from any or all of the Resource Management Act requirements, enabling the destruction of biodiversity and pollution of rivers and coasts. It also scrapped every positive action to reduce emissions, ignoring both the MfE ‘Our atmosphere and climate’ report and the Climate Change Commission’s latest report. It plans to open up conservation lands to mining and the ocean to drilling for oil and gas.This puts us on a catastrophic path to the future, turning Aotearoa into a ‘pariah state’ as the rest of the planet heats up at an accelerating rate.
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2025
- In his first day in office, newly elected President Donald Trump withdraws from the Paris Accord, signs legislation to ban offshore wind turbines, and declares, ‘drill baby drill’ for more oil and gas to address an ‘energy emergency’ in the U.S.
- Auckland: more than 4000 homes have been consented in floodplains since the 2023 storms. One flood damaged home is set to be replaced with seven new townhouses on land deemed unsafe for vulnerable people and vehicles.
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The government of New Zealand has been labelled a “disgrace” after it released a new climate plan which barely requires it to reduce emissions between 2030 and 2035. – Climate Change News 2025
- Three of New Zealand’s biggest emitters no longer have to reveal their climate impact: If you don’t measure it, it doesn’t count…For the first time, the Environmental Protection Authority (EPA)’s company-level emissions data doesn’t include agriculture, after the government ended compulsory reporting for the farming sector.”
- The Government
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2026 to February
- Calling climate change a hoax, Trump pulls US out of 66 international bodies, including key UN climate treaty and dismantles or defunds critical climate, and weather monitoring systems including the National Center for Atmospheric Research (NCAR), NOAA’s Office of Oceanic and Atmospheric Research and has cancelled NASA climate satellite missions.
- Calls for climate engineering are increasing: this article examines each method’s risks.
- By mid-February, across Aotearoa eight ‘Severe weather States of Emergency’ had been declared, matching the total for all of 2025.
- AA Insurance will no longer issue new policies in Westport due to flood risk
- NZ Government refuses to reveal the details of why it undermined a solar rooftop initiative and instead plans for taxpayers to fund a new billion-dollar liquified natural (LNG) gas terminal in Taranaki
- March: Iran retaliates to attacks by Israel and the U.S. by closing the Straight of Hormuz, thereby cutting off ~20% of global oil and LNG exports, leading to increased prices
Instructions for interactive graphs (Credit: The 2°
- Mouse over anywhere on the graphs to see the changes over the last thousand years.
- To see time periods of your choice, hold your mouse button down on one section then drag the mouse across a few years, then release it.
- To see how this compares to the past 800,000 years, click on the ‘time’ icon on the top left.
- To return the graphs to their original position, double-click the time icon.
The story of the fossil fuel industry’s multi-million dollar campaign to create political and public mistrust of climate science is outside the scope of this website, however it is well documented by Pulitzer Prize winning 
Greenhouses work