Climate-related security risks have far-reaching implications for the way the world manages peace and security. Climate security is a concept that summons the idea that climate-related change amplifies existing risks in society that endangers the security of humans, ecosystems, economy, infrastructure and societies. Also climate actions to adapt and mitigate impacts can have a negative effect on human security if mishandled.
Climate security refers to the security risks induced, directly or indirectly, by changes in climate patterns. The Global Risks Report 2019 by the World Economic Forum, cited climate change among the most concerning issues. As part of the report a survey cited extreme weather, lack of climate action and natural disasters as the main three problems. The 2017 Global Catastrophic Risks report, issued by the Global Challenges Foundation, highlighted a broad range of security-related topics, among them climate change, and concluded that global warming has a high likelihood to end civilization. The Global Security Defense Index on climate change evaluates the extents of governments in considering climate change to be a national security issue. Policy interest in climate security risks has grown rapidly and affects the policy agenda in relation to, among other questions, food and energy security, migration policy, and diplomatic efforts. Recognizing that the impact of climate change is spread unevenly across different regions, it remains clear that this is a global challenge which will affect all countries in the long-term. However, there may a disproportional effect in fragile contexts and/or socially vulnerable and marginalized groups.
The 2018 Worldwide Threat Assessment report states:
The past 115 years have been the warmest period in the history of modern civilization, and the past few years have been the warmest years on record. Extreme weather events in a warmer world have the potential for greater impacts and can compound with other drivers to raise the risk of humanitarian disasters, conflict, water and food shortages, population migration, labor shortfalls, price shocks, and power outages. Research has not identified indicators of tipping points in climate-linked Earth systems, suggesting a possibility of abrupt climate change.
Within academia, climate security is part of environmental security and was first mentioned in the Brundtland Report in 1987. Thirty years later, experts and scientists in fields as politics, diplomacy, environment and security have used this concept in an increasing frequency. Climate security refers to the security risks induced, directly or indirectly, by changes in the natural climate. There is high agreement that climate change intimidates security where the term ‘security’ can refer to a broad range of securities involving national, international and Human Security. Human Security is the most fragile as it can be compromised in order to protect national or international security.
Scholars analysing conflicts with a climate security rendering have long argued that climate change can adversely affect security and international stability. Research has examined ‘indirect pathways between climate stress and conflict’ — through factors like economic growth, food price shock and forced displacement apart from other types of shock such as: income and livelihood shock (with the accompanying caveats in the table). Climate change can threaten human security by impacting economic growth, food price stock, undermining livelihoods, and prompting displacement. Moreover, there has been reports of collapse of pastoral societies, terrorist groups seeking recruits in dehydrated lands, and flooding ultimately feeding anti-government sentiments. Unstable regions appear to be incapable of surviving climate change-related stresses; instead creating fertile soil for radicalisation, poverty and violent conflict. Scholars of climate security can analyse the chronological order of an escalation, where a changing environment or climate change can be an underlying variable. It is a complex interplay of many political and socio-economical factors where climate change is considered a risk- or threat-multiplier.
During the 70's and 80's the Jason advisory group, concerned with security, conducted research on climate change. Climate change has been identified as a threat multiplier, which can exacerbate existing threats. A 2013 meta-analysis of 60 previous peer-reviewed studies, and 45 data sets concluded that, "climate change intensifies natural resource stresses in a way that can increase the likelihood of livelihood devastation, state fragility, human displacement, and mass death."
In the 2014 Quadrennial Defense Review (QDR), The Pentagon stated: "The QDR will set a long-term course for DOD as it assesses the threats and challenges that the nation faces and re-balances DOD’s strategies, capabilities, and forces to address today’s conflicts and tomorrow’s threats." and " "As greenhouse gas emissions increase, sea levels are rising, average global temperatures are increasing, and severe weather patterns are accelerating [...] Climate change may exacerbate water scarcity and lead to sharp increases in food costs. The pressures caused by climate change will influence resource competition while placing additional burdens on economies, societies, and governance institutions around the world. These effects are threat multipliers that will aggravate stressors abroad such as poverty, environmental degradation, political instability, and social tensions – conditions that can enable terrorist activity and other forms of violence."  Climate scientist Michael E. Mann stated in his commentary to the 2018 global heat wave that climate change is a national security nightmare.
A report in 2003 by Peter Schwartz and Doug Randall, looked at potential implications from climate-related scenarios for the national security of the United States, and concluded, "We have created a climate change scenario that although not the most likely, is plausible, and would challenge United States national security in ways that should be considered immediately." Among the findings were:
"There is a possibility that this gradual global warming could lead to a relatively abrupt slowing of the ocean's thermohaline conveyor, which could lead to harsher winter weather conditions, sharply reduced soil moisture, and more intense winds in certain regions that currently provide a significant fraction of the world's food production. With inadequate preparation, the result could be a significant drop in the human carrying capacity of the Earth's environment."
Researchers studying ancient climate patterns (paleoclimatology) noted in a 2007 study:
We show that long-term fluctuations of war frequency and population changes followed the cycles of temperature change. Further analyses show that cooling impeded agricultural production, which brought about a series of serious social problems, including price inflation, then successively war outbreak, famine, and population decline.
A 2013 review by the U.S. National Research Council assessed the implications of abrupt climate change, including implications for the physical climate system, natural systems, or human systems. The authors noted, "A key characteristic of these changes is that they can come faster than expected, planned, or budgeted for, forcing more reactive, rather than proactive, modes of behavior." A 2018 meta study cited cascading tipping elements, which could trigger self-reinforcing feedbacks that progress even when man-made emissions are reduced, and which could eventually establish a new hothouse climate state. The authors noted, "If the threshold is crossed, the resulting trajectory would likely cause serious disruptions to ecosystems, society, and economies." 
Studies identified uptake in mortality due to extreme heat waves. Extreme heat conditions can overcome the human capacity to thermo regulate; future scenarios with rising emissions could expose about 74% of the world population for at least twenty days per year to lethal heat events.
Consequences of psychosocial impacts caused by climate change include: increase in violence, intergroup conflict, displacement and relocation and socioeconomic disparities. Based on research, there is a causal relationship between heat and violence and that any increase in average global temperature is likely to be accompanied by an increase in violent aggression.
Since climate change has serious and broad implications for societies and human livelihoods, the potential security consequences are far-reaching and complex. In a 2016 article, published by the Bulletin of the Atomic Scientists, the author suggested that conflict over climate related water issues, could lead to nuclear conflict, involving Kashmir, India and Pakistan. Based on reviewing 60 studies on the subject of climate change and conflicts, additional to warmer temperatures, more extreme rainfall could increase interpersonal violence by 4%, and intergroup conflict by 14% (median estimates). The violent herder–farmer conflicts in Nigeria, Mali, Sudan and other countries in the Sahel region have been exacerbated by climate change.
Experts have suggested links to climate change in several major conflicts:
The direct nexus between climate and conflict is contested. The most immediate insight gained from quantitative research on climate and conflict is that the two phenomena are connected in a complex and indirect way. The Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report also notes that several factors that increase general conflict risk are sensitive to climate change, but there is no direct and simple causal association between nature and society.
At least since 2010, the U.S. military begun to push aggressively to develop, evaluate and deploy renewable energy to decrease its need to transport fossil fuels. Based on the 2015 annual report from NATO, the alliance plans investments in renewables and energy efficiency to reduce risks to soldiers, and cites the impacts from climate change on security as a reason.
The transnational character of climate-related security risks often goes beyond the capacity of national governments to respond adequately. Many parts of governments or state leaders acknowledge climate change as an issue for human security, national or regional security:
Although climate change is first and foremost dealt within the United Nations Framework Convention on Climate Change (UNFCCC) and now also under the Paris agreement, the security implications of climate change do not have an institutional home within the United Nations system, and hence remain largely unaddressed, in spite of the urgency of the threat it poses to peace and security in several regions. The UN, through its COP - The Conference of the Parties - is the supreme body to negotiate climate frameworks under the UNFCCC Convention. It consists of the representatives of the Parties to the Convention and holds its sessions every year, and takes decisions which are necessary to ensure the effective implementation of the provisions of the Convention and regularly reviews the implementation of these provisions.Preventing “dangerous” human interference with the climate system is the ultimate aim of the UNFCCC. The UNFCCC is a “Rio Convention”, one of three adopted at the “Rio Earth Summit” in 1992. The UNFCCC entered into force on 21 March 1994. Today, it has near-universal membership. The COP has discussed Climate Security during panels, workshops as session, but not as a programmatic track. The greater focus on this topic by the UN has led to the launch in October 2018 of the inter-agency DPPA-UNDP-UN Environment cooperation called the ‘Climate Security Mechanism’.
The UN Security Council first debated climate security and energy in 2007 and in 2011 issued a presidential statement expressing concern at the possible adverse security effects of climate change. There has been a series of informal Arria-Formula meetings on issues related to climate change. In July 2018, Sweden initiated a debate on Climate and Security in the United Nations Security Council. Climate change grew beyond its categorisation as a hypothetical, existential risk and became an operational concern of relevance to other peace and security practitioners beyond the diplomats in the Security Council.
The European Council’s conclusions on climate diplomacy state that "Climate change is a decisive global challenge which, if not urgently managed, will put at risk ... peace, stability and security."  The Intelligence on European Pensions and Institutional Investment think-tank published a 2018 report with the key point, "Climate change is an existential risk whose elimination must become a corporate objective". In June 2018 European External Action Service (EEAS) High-Level Event hosted an event themed "Climate, Peace and Security: The Time for Action". The EU's comprehensive approach to security would suggest that the EU is well placed to respond to climate-related security risks. However, recent scientific research shows that the European Union has not yet developed a fully coherent policy. 
US intelligence analysts have expressed concern about the "serious security risks" of climate change since the 1980s. In 2007, the Council on Foreign Relations released a report titled, Climate Change and National Security: An Agenda for Action, stating that "Climate change presents a serious threat to the security and prosperity of the United States and other countries." A 2012 report published by the Joint Global Change Research Institute indicated that second and third order impacts of climate change, such as migration and state stability, are of concern for the US defense and intelligence communities. A 2015 report published by the White House found that climate change puts coastal areas at risk, that a changing Arctic poses risks to other parts of the country, risk for infrastructure, and increases demands on military resources. In 2016, Director of National Intelligence James Clapper noted: "Unpredictable instability has become the “new normal,” and this trend will continue for the foreseeable future…Extreme weather, climate change, environmental degradation, rising demand for food and water, poor policy decisions and inadequate infrastructure will magnify this instability."
A 2015 Pentagon report pointed out how climate denial threatens national security. In 2017, the Trump administration removed climate change from its national security strategy. But in January 2019 the Pentagon released a report stating that climate change is a national security threat to USA. In June 2019, in the course of House Select Committee on Intelligence hearings on the national security implications of climate change, the White House blocked the submission of a statement by the State Department's Bureau of Intelligence and Research Office, and the analyst who wrote the statement resigned. The idea of creating a presidential committee on climate security has been proposed. As part of the United States National Defense Authorization Act the U.S. Congress asked the Department of Defense for a report on climate matters. The report was published in 2019, and notes, "The effects of a changing climate are a national security issue with potential impacts to Department of Defense (DoD or the Department) missions, operational plans, and installations."
A 2018 published report by the Australian Senate noted, "climate change as a current and existential national security risk… defined as one that threatens the premature extinction of Earth-originating intelligent life or the permanent and drastic destruction of its potential for desirable future development." 
In 2014, David Cameron noted, "Climate change is one of the most serious threats facing our world", A 2018 article in UK's The Independent argues that the U.S. Trump administration is ‘putting British national security at risk’, according to over 100 climate scientists.
The 2010 documentary, Carbon Nation explores climate change solutions. The Guardian noted about Carbon Nation, "The take-home message is that what's good for the climate is also good for the economy, for national security, for health, for nature – and for America." The documentary The Burden presents the argument for a switch from fossil fuel reliance to clean energy from a military perspective. Bob Inglis is quoted, "I see incredible opportunity.... We improve our national security. We create jobs and we clean up the air."
In 2014, Leonardo DiCaprio stated during a United Nations conference, "The time to answer the greatest challenge of our existence on this planet is now. You can make history or be vilified by it." At a 2015 security conference, Arnold Schwarzenegger called climate change the issue of our time.