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." The 2014 report, by the CNA Military Advisory Board, "National Security and the Accelerating Risks of Climate Change" re-examined the impact of climate change on U.S. national security. The report concluded that climate change is a growing security threat.
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. The NATO stated in 2015 that climate change is significant security threat and ‘Its Bite Is Already Being Felt’.
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.
The Global Security Defense Index on climate change evaluates the extents of governments in considering climate change to be a national security issue.
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."
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.
Experts have suggested links to climate change in several major conflicts:
"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."
"Climate change poses another significant challenge for the United States and the world at large. As greenhouse gas emissions increase, sea levels are rising, average global temperatures are increasing, and severe weather patterns are accelerating. These changes, coupled with other global dynamics, including growing, urbanizing, more affluent populations, and substantial economic growth in India, China, Brazil, and other nations, will devastate homes, land, and infrastructure. 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."
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.
Many parts of governments or state leaders acknowledge climate change as a problem for national security, i.e. Barack Obama David Cameron, or former United States Secretary of Defense, Chuck Hagel.
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.
A RAND Corporation blog noted in 2015, "Climate change can affect conflict around the world in uncertain and complex ways, although we can't establish the magnitude of a causal relationship with confidence. In addition, there are unresolved hypotheses about indirect climate-security linkages, such as destabilization."
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 argues for a switch from fossil fuel reliances to clean energies 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."