Climate change refers to gradual alternation in Earth’s climate system leading to long-term transition in temperature and weather patterns. Historically, planet Earth has passed through various phases of climate change and has fluctuated between extremely hot and cold climates. These changes were caused by natural factors like volcanic eruptions, asteroid strike, intensification of solar activity, and natural concentration of greenhouse gases. For example, during Cretaceous period (144 to 65 million years ago), Earth’s temperature was much higher than today due to high content of carbon-di-oxide (CO2)in atmosphere, leading to rise in ocean level. Similarly, in past 500,000 years, at-least four ice ages have passed which resulted in decline of global temperature, reduction in sea level, and expansion of glaciers on planet’s surface. These climate variations have caused extinction of many species, but many species have thrived too. However, the current challenge of climate change which we are facing is anthropogenic in nature, i.e. it has been caused by human activity and is something which has never occurred in planet’s history. Therefore, uncertainty surrounds regarding our planet’s capacity to recover from damages caused by humanity like pollution, deforestation, and destruction of natural habitat through urbanization.
Humanity’s journey toward climate change awareness has been a testament to the growing recognition of our shared responsibility to protect the planet. Initial understanding about greenhouse effect was theorized by French mathematician and physicist Joseph Fourier in 1820s. In 1950s, Fourier’s proposal was further elaborated through experimentation by Eunice Foote – who can be regarded as climate science pioneer of that era. Her experiments, involving glass cylinders, proved that the solar heating effect is more evident in moist air – containing higher concentration of CO2, than dry air. In the 1860s, experiments of John Tyndall, who is attributed as discoverer of green-house effect, also revealed that coal gas containing mixture of carbon-di-oxide (CO2), methane (CH4) and other volatile hydrocarbons, effectively absorb sunlight, with CO2 uniquely acting like a sponge by capturing multiple wavelengths of sunlight. By 1895, Svante Arrhenius, had proven the direct relationship between CO2 and global temperature. His calculations showed that if CO2 concentration is halved, temperature would reduce by 50 percent. However, if CO2 concentration is doubled, corresponding increment in temperature would take place. Although the work of these scientists laid foundation of early understanding of climate change, but they didn’t receive any credible attention due to remote nature of threat of climate change
As humanity entered the 20th century, the carbon foot-print of industrialization had increased substantially. However, the concept of climate change was still viewed with skepticism. In 1938, British engineer Guy Stewart Callendar became the first person to discover the relationship between human activity and planet’s rising temperature. His theory, called ‘the Challendar Effect,’ also didn’t receive the acceptability it deserved, but at least it managed to identify and attract attention towards upcoming threat of global warming.
In 1958, Charles Keelung created Keling Curve to demonstrate the gradual increment of CO2 in the atmosphere by utilizing his measurements at Mauna Lao. His work marked a major contribution in analyzing the future threat of rising temperature due to increasing concentration of CO2 in atmosphere. Beside previous individual efforts, perhaps the biggest leap was the organization of United Nations’ Conference on Human Environment in Stockholm, Sweden, in 1970. This summit, for the first time, highlighted the growing concerns associated with climate change on international scale and marked the initiation of discussions between developed and developing countries on the relation between economic growth, pollution and human well-being. By 1975, term ‘global warming’ had been crafted by Wallace Broecker, a geochemist and professor at Columbia University. In 1979, first World Climate Conference, sponsored by World Meteorological Organization, was held in Geneva, Switzerland. This conference led to the establishment of the World Climate Programme (WCP). The conference’s declaration called for: A common strategy to understand the climate system, rational use of climate information, and Establishment of the WCP.
In 1985, ozone hole was discovered by British Antarctic Survey scientists Joe Farman, Brian Gardiner, and Jonathan Shanklin. This hole was byproduct of wide-scale adaptation of Ozone Depleting Substances (ODS) particularly Chlorofluorocarbons. To curb usage of ODS and restore ozone hole, Montreal Protocol was signed in 1987. The effective implementation of protocol has led to remarkable recovery of ozone layer which is expected to fully recover in next four decade. Montreal Protocol, thus, represents humanity’s first success against climate change.
In 1988, The Intergovernmental Panel on Climate Change (IPCC) was established to assess climate science and provide policymakers with insights. So far, IPCC has presented six assessments reports. The First Assessment Report (1990) highlighted climate change as a global issue, leading to the creation of the United Nations Framework Convention on Climate Change (UNFCCC). The Second Report (1995) informed the adoption of the Kyoto Protocol (1997), while the Third Report (2001) emphasized the impacts of climate change and adaptation. The Fourth Report (2007) focused on limiting warming to 2°C, laying the groundwork for post-Kyoto agreements. The Fifth Report (2013-2014) provided the scientific basis for the Paris Agreement, and the Sixth Report (2023) supported the first global stocktake at the end of 2023. These assessment reports have played important role in climate awareness and have significantly shaped climate policies around the globe.
The Kyoto Protocol was established in 11 December 1997 and came into force on 16 February 2005. In brief, Kyoto Protocol operationalized the UNFCCC by committing developed economies and industrialized nations to develop and implement policies for minimizing emissions of greenhouse gases (GHG). These countries committed to curb collective GHG emissions by 5 percent during first commitment period (2008-2012). However, despite being a milestone the protocol faced criticism for not including major developing nations from binding commitments and for the withdrawal of key emitters like the United States.
The Kyoto Protocol was eventually succeeded by Paris Agreement in 2015 which was adopted at the 21st Conference of Parties (COP21) and entered into force on 4 November 2016. With 196 parties, the agreement covers the entire globe. Paris Agreement has primary goal of holding the global average temperature increment below 2°C and to limit the temperature increase to 1.5°C above pre-industrial levels. However, the agreement is struggling to meet even the minimum expectations. The Paris Agreement, hailed as a pivotal achievement by humanity for climate action, is struggling to meet even the minimum. The United Nations Environment Programme’s 2024 Emissions Gap Report highlights that current greenhouse gas emissions are too high to meet the agreement’s goals. Without significant strengthening of Nationally Determined Contributions (NDCs), the planet is projected to warm by +3.1°C by century’s end. These challenges highlight the reality that agreements alone cannot solve the climate crisis—sustained action, innovation, and global cooperation are crucial.
The awareness about climate change has spread gradually. From the early warnings of climate science to landmark agreements like the Kyoto Protocol and the Paris Agreement, global efforts have evolved to address the mounting threats posed by a changing climate. However, the journey is far from over. This journey of climate change awareness must now transform into a journey of climate action—one where every nation, community, and individual plays their part in creating a sustainable and resilient future for all.
