Sfetcu, Nicolae (2023), The Science of Climate Change, MultiMedia, DOI: 10.13140/RG.2.2.25387.62247, https://www.telework.ro/en/the-science-of-climate-change/

 

Abstract

Climate change is one of the most pressing challenges facing our planet today. Climate change science is a multidisciplinary field that studies the long-term patterns and variations of the Earth’s climate and the factors that influence them. It aims to understand the mechanisms driving climate change, its impacts and potential mitigation and adaptation strategies. Today, complex computer models representing a wide range of climate system processes are a mainstay of climate research.

Keywords: climate change, global warming, climate change science, climate change engineering, climate change mitigation, climate change adaptation

 

The Science of Climate Change

Nicolae Sfetcu[1]

nicolae@sfetcu.com

[1] Researcher – Romanian Academy – Romanian Committee for the History and Philosophy of Science and Technology (CRIFST), History of Science Division (DIS)

 

Introduction

Climate change is the long-term alteration of the Earth’s climate system caused by natural and human factors. Climate change is one of the most pressing challenges facing our planet today. It refers to long-term changes in weather patterns and global temperatures due to human activities and natural processes. The scientific community has overwhelmingly concluded that human activities, particularly the burning of fossil fuels and deforestation, are the main drivers of recent and rapid climate change. Climate change science studies the causes, effects, and projections of these changes, using observations, models, and experiments. This is a multidisciplinary field that studies the long-term patterns and variations of the Earth’s climate and the factors that influence them. It aims to understand the mechanisms driving climate change, its impacts and potential mitigation and adaptation strategies. The main focus is on the role of human activities in modifying the climate system, particularly through the release of greenhouse gases into the atmosphere.

Alarming rates of environmental change have catalyzed scientists to call for fundamental transformations in socio-political and economic relations. A relational framing of adaptation and transformation requires a political, transversal and socio-natural analysis to probe the affects and effects of climate change and to better understand how transformative change unfolds. Effective transformation requires recognizing uncertainty and unpredictability as part of transformation processes.

The field of climate science emerged in the second half of the 20th century. Climate science aims to explain and predict the workings of a global climate system — which includes the atmosphere, oceans, land surface, ice sheets, and more — and makes extensive use of both theoretical knowledge and mathematical modeling. The emergence of climate science is closely related to the rise of digital computing, which made it possible to simulate large-scale motions of the atmosphere and oceans using fluid dynamical equations that were otherwise intractable; these motions transport mass, heat, moisture, and other quantities that shape paradigmatic climate variables such as mean surface temperature and precipitation. Today, complex computer models representing a wide range of climate system processes are a mainstay of climate research.

Key concepts

Greenhouse effect

The greenhouse effect is the process by which certain gases in the atmosphere trap heat and warm the planet. Without the greenhouse effect, Earth would be too cold to support life.

Earth’s atmosphere contains natural greenhouse gases such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and water vapor. These gases trap heat from the sun, creating the natural greenhouse effect. Human activities have significantly increased the concentration of these greenhouse gases, primarily through the burning of fossil fuels for energy, deforestation and industrial processes. This increased greenhouse effect leads to climate change and finally to global warming.

The carbon cycle involves the movement of carbon between different reservoirs, such as the atmosphere, oceans, land, and living organisms. It affects the level of greenhouse gases in the atmosphere and the acidity of the oceans.

Evidence of climate change

The climate system consists of the complex interaction of the atmosphere, oceans, land, ice, and biosphere that determine Earth’s climate. The climate system is influenced by external factors such as solar radiation and volcanic eruptions, as well as internal factors such as ocean currents and atmospheric circulation. The climate system exhibits variability on different time scales, from seasons to millennia.

Evidence of climate change comes from a variety of sources that can be used to reconstruct the past climate. From the mid-late 19th century, reasonable data on surface temperatures are available. For earlier periods, most evidence is that indirect climate change is inferred from changes in proxies, indicators that reflect climate, such as vegetation, ice cores, dendrochronology, sea-level change, and glacial geology.

The evidence of climate change is abundant and compelling. Rising global temperatures, melting glaciers and ice caps, more frequent and more intense heat waves, changes in rainfall patterns and rising sea levels are some of the observable effects. In addition, there has been an increase in extreme weather events such as hurricanes, droughts, and floods, all of which have devastating impacts on ecosystems, agriculture, and human settlements.

Climate feedback are the processes that amplify or dampen the response of the climate system to a change in forcing. For example, melting ice reduces surface reflectivity, allowing more solar energy to be absorbed, leading to more warming and more melting. This is positive feedback that improves upon the initial change. On the other hand, increased evaporation from warmer oceans increases cloud cover, which reflects more solar energy back into space, reducing warming. This is negative feedback that counteracts the initial change.

Climate models

There are different ways in which data are obtained in climate science. Ground weather stations measure the temperature of the air near the Earth’s surface using thermometers. A network of free-floating buoys that sink to a depth of about 2000 m, then return to transmit data, then sink again and so on, provide measurements of ocean temperature. Satellites record concentrations of greenhouse gases, aerosols, cloud cover, etc.

Climate models are mathematical representations of the climate system based on physical laws and empirical data. Climate models are used to simulate past, present, and future climates under different scenarios of greenhouse gas emissions and other forcings. Climate models are essential tools for understanding and projecting climate change and its impacts. Computer-based climate models simulate and predict future climate scenarios based on various inputs, including greenhouse gas emissions and solar radiation, helping to understand potential climate changes and their impacts.

The range of temperature projections partly reflects the choice of emissions scenario and the degree of “climate sensitivity”. The projected magnitude of warming by 2100 is closely related to the level of cumulative emissions over the 21st century (i.e., total emissions between 2000 and 2100). The greater the cumulative emissions over this period, the greater the level of warming expected to occur. Climate sensitivity reflects the uncertainty in the response of the climate system to past and future GHG emissions. Higher estimates of climate sensitivity lead to greater projected warming, while lower estimates lead to less projected warming.

Climate model projections summarized in the CISC report indicate that the global surface temperature appears to be increasing by 1.1 to 6.4 °C in the 21st century. The uncertainty in this estimate comes from the use of models with different climate sensitivities to greenhouse gas concentrations, and the use of different estimates regarding the evolution of greenhouse gas emissions. An increase in global temperature will lead to a rise in sea levels and change the amount and pattern of precipitation, possibly including the expansion of subtropical deserts. Warming is expected to be greatest in the Arctic, and to be associated with continued retreat of glaciers, cryogenic soil and sea ice. Other possible effects include changes in the frequency and intensity of extreme weather events, the extinction of some species, and changes in agricultural production. Warming and other related changes will vary from region to region, the nature of these major changes not yet known. As a result of the current increase in carbon dioxide in the atmosphere, the oceans have become more acidic, and this effect is expected to continue.

Human activities as a primary cause

Do rising temperatures indicate that climate change is occurring, and if so, can the change be attributed to human action? These two problems are known as detection and assignment problems. Intuitively, climate change detection is the process of determining that there has been a significant change in observed variables of the climate system without providing a reason for that change.

There is a scientific consensus in the existence of anthropogenic global warming, due to man. Although natural processes can influence climate, the current rate of climate change cannot be explained by these factors alone. Scientists have determined that human activities are the dominant cause of recent increases in greenhouse gas concentrations. Burning fossil fuels for electricity, transport, and industrial production releases large amounts of CO2 into the atmosphere. Deforestation also plays an important role, as trees absorb CO2 and help regulate the climate, as do industrial processes and agriculture.

The long-term increase in the average temperature of the Earth’s surface and lower atmosphere is known as global warming. It has been observed for the past century and is primarily attributed to human activities. The last decade has seen increased anthropological attention to understanding climate change not only as a biophysical phenomenon, but also as a discourse spreading from international policy-making platforms to the rest of the planet. Analysis of climate change discourse uptake falls within the emerging subfield of climate change reception studies.

Consequences of climate change

The effects of climate change on the environment are broad and far-reaching, affecting the oceans, ice, and weather. Changes can occur gradually or rapidly. Evidence for these effects comes from studying past climate change, from modeling, and from modern observations. Since the 1950s, drought and heat waves have occurred simultaneously with increasing frequency. Extremely wet or dry monsoon events have increased in India and East Asia. The rate and intensity of rainfall from hurricanes and typhoons is increasing.

Climate change poses significant risks to the environment, economies, and human well-being. Rising temperatures disrupt ecosystems, threaten biodiversity and lead to changes in habitat ranges for many species. Climate change affects various aspects of the environment and human societies, including sea level rise, extreme weather events (e.g., hurricanes, heat waves, floods), changes in precipitation patterns, disruption of ecosystems, impacts on agriculture and food security, as threats to human health.

Many physical effects of climate change are already visible, including extreme weather events, retreating glaciers, changes in the timing of seasonal events (e.g., earlier flowering of plants), rising sea levels, and shrinking Arctic ice. The ocean has absorbed 20% to 30% of human-induced atmospheric carbon dioxide since the 1980s, leading to ocean acidification. The ocean is also warming, and since 1970 has absorbed more than 90% of the excess heat from the climate system.

The effects of climate change on humans, largely due to warming and changes in precipitation, have been detected worldwide. Impacts are now visible on all continents and in oceanic regions, with low-latitude, less developed areas facing the greatest risk. Continued warming has serious, pervasive, and irreversible effects on people and ecosystems. Risks are unevenly distributed but are generally higher for disadvantaged people in developing and developed countries.

Mitigation and adaptation

To address climate change, both mitigation and adaptation strategies are essential. Mitigation involves efforts to reduce greenhouse gas emissions, switch to renewable energy sources, improve energy efficiency, and implement sustainable land use practices. On the other hand, adaptation focuses on preparing for and managing the impacts of climate change that are already unavoidable. Adaptation involves strategies to deal with existing and anticipated impacts of climate change to minimize negative consequences, including building resilient infrastructure, developing early warning systems for extreme weather events, and improving agricultural practices to cope with changing conditions.

Mitigation of climate change represents actions to reduce greenhouse gas emissions or to increase the capacity of carbon reservoirs to absorb greenhouse gases from the atmosphere. There is great potential for future emissions reduction through a combination of activities, including energy conservation and increased energy efficiency; the use of low-carbon energy technologies such as renewable energy, nuclear power and carbon capture and storage; as well as strengthening carbon pools through, for example, reforestation and preventing deforestation.

Adaptation is particularly important in developing countries, as these countries are expected to bear the effects of global warming. Respectively people’s ability and potential to adapt (called adaptive capacity) are unevenly distributed among different regions and populations, and developing countries generally have less adaptive capacity.

Climate engineering (sometimes called geoengineering or climate intervention) is the deliberate modification of the climate. This has been investigated as a possible response to global warming, e.g., by NASA and the Royal Society. The techniques investigated generally fall into the categories of solar radiation management and carbon dioxide removal, although various other schemes have been suggested. A 2014 study investigated the most common methods of climate engineering and concluded that they are either ineffective or have severe potential side effects and climate change cannot be stopped without causing rapid change.

Global cooperation and challenges

Climate change is a global problem that requires international cooperation and collective action. Various international agreements, such as the Paris Agreement, aim to bring countries together to set emission reduction targets and promote a global commitment to combat climate change. This international treaty aims to limit global warming to well below 2 degrees Celsius above pre-industrial levels and continue efforts to limit temperature increase to 1.5 degrees Celsius. However, there are challenges in implementing these agreements as they require cooperation between nations with diverse economic, social, and political interests. Most countries are parties to the United Nations Framework Convention on Climate Change (UNFCCC), whose goal is to prevent dangerous anthropogenic climate change.

Climate change is a critical issue that transcends national borders and socio-economic-political spheres. Due to the pervasive and deep-rooted nature of its causes, researchers and policymakers face a massive task of coordinating and developing effective policies to mitigate its impact. To complicate matters, worsening conditions and ineffective strategies developed to deal with the problems became another pressing concern. Developing and coordinating a research and policy agenda for climate change mitigation and adaptation is the cornerstone for making substantial progress.

Conclusion

The science of climate change is mature, and the evidence overwhelmingly points to human activities as the main driver of this global challenge. The consequences of climate change are far-reaching, affecting ecosystems, economies, and people’s livelihoods. Urgent action is needed to mitigate emissions and adapt to climate change. Individuals, governments, and businesses must work together to reduce greenhouse gas emissions, promote sustainable practices and adopt cleaner technologies. Only through concerted global efforts can we hope to tackle the science of climate change and ensure a sustainable future for generations to come.

 

This is an Open Access article distributed under the terms of the license Creative Commons CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/).