The response to climate change

The response to climate change

(Image: Andreas Gulklhorn)

A short history of climate change: who knew what, when

“The effects will indeed be catastrophic (at least for a substantial fraction of the world’s population).”ExxonMobil

“Rather than warn the public, Exxon spent over $30 million on climate-denying think tanks and researchers to confuse the public about climate science—a confusion that persists to this day—while doubling down on its destructive business model. “               – Wasserman, NY Times

We’ve known about greenhouse gasses and the impact of carbon dioxide (CO2) on the climate for a very long time


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.



[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.



[CO2 in the atmosphere: 285.6 ppm]

Eunice Foote’s research on how increasing ‘carbonic acid’carbon dioxidein 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.

Fig. 1: (Image: The American Journal of Science and Arts)



[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 gasses trap heat in the atmosphere (see: ‘What causes climate change‘ this website). 



[CO2 in the atmosphere: 294.9 ppm]

Swedish scientist Svante Arrhenius realised that burning fossil fuels adds carbon dioxide to the atmosphere, and that may eventually cause global warming.



[CO2 in the atmosphere: 300.4 ppm]

The Rodney and Otamatea Times (NZ) reported that burning coal will affect the climate (Fig. 2).

Fig. 2.
Fig. 2.



[CO2 in the atmosphere: 314.9 ppm]

Scientists started tracking CO2 concentrations at Mauna Loa observatory in Hawaii.



[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.

Fig. 3. (Image: Inside Climate News)
Fig. 3. (Image: Inside Climate News)



[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.



[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



[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’.



[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.



[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.



[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.



[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.



[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.



[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.



[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.



[CO2 in the atmosphere: 401 ppm]

By now, 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.



[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: 

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.



[CO2 in the atmosphere: 415 ppm]

[Average global temperature increase since 1850: 1.2°C]

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 gasses to keep climate change under dangerous levels.



 Instructions for  interactive graphs (Credit: The Institute.)

  • 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.



Greenhouses work by convection, while atmospheric heating works by absorption and emission of electromagnetic radiation, preventing absorbed heat from leaving the atmosphere through radiative transfer (RT), which is affected by the individual chemical properties of different greenhouse gasses.

Physics and chemistry of climate change:

These are well understood and accepted laws. Although not always easily understand for those without degrees in physics, chemistry and/or maths, we use these laws every day. They work in our cars and mobile phones, every time we turn on an electrical appliance or take many of our medicines. These are the main ones:

  • The Law of Conservation of Energy, a basic law of thermodynamics, which states that: ‘Energy can neither be created nor destroyed; rather, it can only be transformed or transferred from one form to another.’
  • The Stefan-Boltzmann Law
  • The Clausius-Clapeyron Equation for describing a discontinuous phase transition between the different states (gas, liquid, solid) of water.
  • The isotopic fingerprint of CO2 (3 minutes video explaining this)


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 Inside Climate News (comprehensive library of documents) and science historian Professor Naomi Oreskes in her book and documentary: Merchants of Doubt and/or her lecture: Video 2.

Video 2

References and further reading