The control of fire by early humans was a turning point in the technological evolution of human beings. Fire provided a source of warmth, protection from predators, a way to create more advanced hunting tools, and a method for cooking food. These cultural advances allowed human geographic dispersal, cultural innovations, and changes to diet and behavior. Additionally, creating fire allowed human activity to continue into the dark and colder hours of the evening.

Claims for the earliest definitive evidence of control of fire by a member of Homo range from 1.7 to 2.0 million years ago (Mya).^[1] Evidence for the "microscopic traces of wood ash" as controlled use of fire by Homo erectus, beginning some 1,000,000 years ago, has wide scholarly support.^[2][3] Flint blades burned in fires roughly 300,000 years ago were found near fossils of early but not entirely modern Homo sapiens in Morocco.^[4] Fire was used regularly and systematically by early modern humans to heat treat silcrete stone to increase its flake-ability for the purpose of toolmaking approximately 164,000 years ago at the South African site of Pinnacle Point.^[5] Evidence of widespread control of fire by anatomically modern humans dates to approximately 125,000 years ago.^[6] They also used fire for light.

The colorful microbial mats of Grand Prismatic Spring in Yellowstone National Park, USA. The orange mats are composed of Chloroflexi, Cyanobacteria, and other organisms that thrive in the 70˚C water. Geobiologists often study extreme environments like this because they are home to extremophilic organisms. It has been hypothesized that these environments may be representative of early Earth.^[1]

Geobiology is a field of scientific research that explores the interactions between the physical Earth and the biosphere. It is a relatively young field, and its borders are fluid. There is considerable overlap with the fields of ecology, evolutionary biology, microbiology, paleontology, and particularly soil science and biogeochemistry. Geobiology applies the principles and methods of biology, geology, and soil science to the study of the ancient history of the co-evolution of life and Earth as well as the role of life in the modern world.^[2] Geobiologic studies tend to be focused on microorganisms, and on the role that life plays in altering the chemical and physical environment of the pedosphere, which exists at the intersection of the lithosphere, atmosphere, hydrosphere and/or cryosphere. It differs from biogeochemistry in that the focus is on processes and organisms over space and time rather than on global chemical cycles.

Geobiological research synthesizes the geologic record with modern biologic studies. It deals with process - how organisms affect the Earth and vice versa - as well as history - how the Earth and life have changed together. Much research is grounded in the search for fundamental understanding, but geobiology can also be applied, as in the case of microbes that clean up oil spills.^[3]

Geobiology employs molecular biology, environmental microbiology, chemical analyses, and the geologic record to investigate the evolutionary interconnectedness of life and Earth. It attempts to understand how the Earth has changed since the origin of life and what it might have been like along the way. Some definitions of geobiology even push the boundaries of this time frame - to understanding the origin of life and to the role that man has played and will continue to play in shaping the Earth in the Anthropocene.^[4]

Defaunation is the global, local or functional extinction of animal populations or species from ecological communities.^[1] The growth of the human population, combined with advances in harvesting technologies, has led to more intense and efficient exploitation of the environment.^[2] This has resulted in the depletion of large vertebrates from ecological communities, creating what has been termed "empty forest".^[3][4][5] Defaunation differs from extinction; it includes both the disappearance of species and declines in abundance.^[6] Defaunation effects were first implied at the Symposium of Plant-Animal Interactions at the University of Campinas, Brazil in 1988 in the context of Neotropical forests.^[7] Since then, the term has gained broader usage in conservation biology as a global phenomenon.^[8][1]

It is estimated that more than 50 percent of all wildlife has been lost in the last 40 years.^[9] in 2020 it is estimated that 68% of the world's wildlife will be lost.^[10] In South America, there is believed to be a 70 percent loss.^[11]

In November 2017, over 15,000 scientists around the world issued a second warning to humanity, which, among other things, urged for the development and implementation of policies to halt "defaunation, the poaching crisis, and the exploitation and trade of threatened species."^[12]

Sustainable forest management (SFM) is the management of forests according to the principles of sustainable development. Sustainable forest management has to keep the balance between three main pillars: ecological, economic and socio-cultural. Successfully achieving sustainable forest management will provide integrated benefits to all, ranging from safeguarding local livelihoods to protecting the biodiversity and ecosystems provided by forests, reducing rural poverty and mitigating some of the effects of climate change.^[1]

The "Forest Principles" adopted at the Earth Summit (United Nations Conference on Environment and Development) in Rio de Janeiro in 1992 captured the general international understanding of sustainable forest management at that time. A number of sets of criteria and indicators have since been developed to evaluate the achievement of SFM at the global, regional, country and management unit level. These were all attempts to codify and provide for independent assessment of the degree to which the broader objectives of sustainable forest management are being achieved in practice. In 2007, the United Nations General Assembly adopted the Non-Legally Binding Instrument on All Types of Forests. The instrument was the first of its kind, and reflected the strong international commitment to promote implementation of sustainable forest management through a new approach that brings all stakeholders together.^[2]

The Sustainable Development Goal 15 is also a global initiative aimed at promoting the implementation of sustainable forest management.^[3]

The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations^[1][2] that is dedicated to providing the world with objective, scientific information relevant to understanding the scientific basis of the risk of human-induced^[3] climate change, its natural, political, and economic impacts and risks, and possible response options.^[4]

The IPCC was established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) and was later endorsed by the United Nations General Assembly. Membership is open to all members of the WMO and UN.^[5] The IPCC produces reports that contribute to the work of the United Nations Framework Convention on Climate Change (UNFCCC), the main international treaty on climate change.^[6][7] The objective of the UNFCCC is to "stabilize greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic (human-induced) interference with the climate system".^[8] The IPCC's Fifth Assessment Report was a critical scientific input into the UNFCCC's Paris Agreement in 2015.^[1]

IPCC reports cover the "scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts and options for adaptation and mitigation."^[9] The IPCC does not carry out original research, nor does it monitor climate or related phenomena itself. Rather, it assesses published literature, including peer-reviewed and non-peer-reviewed sources.^[10] However, the IPCC can be said to stimulate research in climate science. Chapters of IPCC reports often close with sections on limitations and knowledge or research gaps, and the announcement of an IPCC special report can catalyse research activity in that area.

Thousands of scientists and other experts contribute on a voluntary basis^[11] to writing and reviewing reports, which are then reviewed by governments. IPCC reports contain a "Summary for Policymakers", which is subject to line-by-line approval by delegates from all participating governments. Typically, this involves the governments of more than 120 countries.^[12]

The IPCC provides an internationally accepted authority on climate change,^[13] producing reports that have the agreement of leading climate scientists and consensus from participating governments. The 2007 Nobel Peace Prize was shared between the IPCC and Al Gore.^[14]

Following the election of a new Bureau in 2015, the IPCC embarked on its sixth assessment cycle. Besides the Sixth Assessment Report, to be completed in 2022, the IPCC released the Special Report on Global Warming of 1.5 °C in October 2018, released an update to its 2006 Guidelines for National Greenhouse Gas Inventories—the 2019 Refinement—in May 2019, and delivered two further special reports in 2019: the Special Report on Climate Change and Land (SRCCL), published online on 7 August, and the Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC), released on 25 September 2019. This makes the sixth assessment cycle the most ambitious in the IPCC's 30-year history.^[15] The IPCC also decided to prepare a special report on cities and climate change in the seventh assessment cycle and held a conference in March 2018 to stimulate research in this area.

Anthropogenic biomes

Anthropogenic biomes, also known as anthromes or human biomes, describe the terrestrial biosphere (biomes) in its contemporary, human-altered form using global ecosystem units defined by global patterns of sustained direct human interaction with ecosystems. Anthromes were first named and mapped by Erle Ellis and Navin Ramankutty in their 2008 paper, "Putting People in the Map: Anthropogenic Biomes of the World".^[1] Anthrome maps now appear in numerous textbooks ^[2] and in the National Geographic World Atlas^[3]

Area of the fertile crescent, c. 7500 BCE, with main archaeological sites of the Pre-Pottery Neolithic period. The area of Mesopotamia proper did not have settlements until later.

The Neolithic Revolution, or (First) Agricultural Revolution, was the wide-scale transition of many human cultures during the Neolithic period from a lifestyle of hunting and gathering to one of agriculture and settlement, making an increasingly large population possible.^[1] These settled communities permitted humans to observe and experiment with plants to learn how they grew and developed.^[2] This new knowledge led to the domestication of plants.^[3][4]

Archaeological data indicates that the domestication of various types of plants and animals happened in separate locations worldwide, starting in the geological epoch of the Holocene 11,700 years ago.^[5] It was the world's first historically verifiable revolution in agriculture. The Neolithic Revolution greatly narrowed the diversity of foods available, resulting in a downturn in the quality of human nutrition.^[6]

The Neolithic Revolution involved far more than the adoption of a limited set of food-producing techniques. During the next millennia it transformed the small and mobile groups of hunter-gatherers that had hitherto dominated human pre-history into sedentary (non-nomadic) societies based in built-up villages and towns. These societies radically modified their natural environment by means of specialized food-crop cultivation, with activities such as irrigation and deforestation which allowed the production of surplus food. Other developments that are found very widely during this era are the domestication of animals, pottery, polished stone tools, and rectangular houses. In many regions, the adoption of agriculture by prehistoric societies caused episodes of rapid population growth, a phenomenon known as the Neolithic demographic transition.

These developments, sometimes called the Neolithic package, provided the basis for centralized administrations and political structures, hierarchical ideologies, depersonalized systems of knowledge (e.g. writing), densely populated settlements, specialization and division of labour, more trade, the development of non-portable art and architecture, and greater property ownership. The earliest known civilization developed in Sumer in southern Mesopotamia (c.  6,500 BP); its emergence also heralded the beginning of the Bronze Age.^[7]

The relationship of the above-mentioned Neolithic characteristics to the onset of agriculture, their sequence of emergence, and empirical relation to each other at various Neolithic sites remains the subject of academic debate, and varies from place to place, rather than being the outcome of universal laws of social evolution.^[8][1] The Levant saw the earliest developments of the Neolithic Revolution from around 10,000 BCE, followed by sites in the wider Fertile Crescent.

Climate engineering or climate intervention,^[1] commonly referred to as geoengineering, is the deliberate and large-scale intervention in the Earth's climate system, usually with the aim of mitigating the adverse effects of global warming.^[2][3][4] The most prominent subcategories of climate engineering are solar radiation management and carbon dioxide removal. Solar radiation management refers to offsetting the warming effect of greenhouse gases by reflecting more solar radiation (sunlight) back into space. Carbon dioxide removal refers to removing carbon dioxide gas (CO
2) from the atmosphere and sequestering it for long periods of time.

Almost all research into solar radiation management has to date consisted of computer modelling or laboratory tests.^[5] A 2014 paper in Nature found that among a variety of climate engineering subcategories including three carbon dioxide removal techniques (afforestation, ocean iron fertilization, and ocean alkalinization), as well as ocean upwelling, only solar radiation management was able to return global average temperatures to pre-industrial levels.^[6]

Climate engineering approaches are sometimes viewed as potential options for limiting climate change or its impacts, alongside mitigation and adaptation.^[7][8] There is substantial agreement among scientists that climate engineering cannot substitute for climate change mitigation (reducing greenhouse gas emissions). Some approaches might be used as accompanying measures to sharp cuts in greenhouse gas emissions.^[1] Given that all types of measures for addressing climate change have economic, political, or physical limitations,^[9][10] some climate engineering approaches might eventually be used as part of an ensemble of measures, which can be referred to as climate restoration.^[11] Research on costs, benefits, and various types of risks of most climate engineering approaches is at an early stage and their understanding needs to improve to judge their adequacy and feasibility.^[12]

Most experts and major reports advise against relying on climate engineering techniques as a main solution to global warming, in part due to the large uncertainties over effectiveness and side effects and unforeseen consequences. However, most experts also argue that the risks of such interventions must be seen in the context of risks of dangerous global warming.^[13][14] Interventions at large scale may run a greater risk of disrupting natural systems resulting in a dilemma that those approaches that could prove highly (cost-)effective in addressing extreme climate risk, might themselves cause substantial risk.^[15] Some^[who?] have suggested that the concept of engineering the climate presents a moral hazard because it could reduce political and public pressure for emissions reduction, which could exacerbate overall climate risks; others assert that the threat of climate engineering could spur emissions cuts.^[16][17][18] Major academic institutions, including Harvard University, have begun research into solar radiation management, viewing it as a potential supplement to, rather than a replacement for, reducing emissions (mitigation).^[19]