"Climate change poses immediate risks to our national security, contributing to increased natural disasters and resulting in humanitarian crises, and potentially increasing refugee flows and exacerbating conflicts over basic resources like food and water," the White House said.

It also aggravates issues at home and abroad, including poverty, political instability and social tensions - conditions that can fuel instability and enable terrorist activity and other forms of violence, the White House said ahead of US President Barack Obama's major speech on climate change.

Climate change is an urgent and growing threat to the US national security, contributing to increased weather extremes which worsen refugee flows and conflicts over basic resources like food and water, it said.

The national security implications of climate change reach far beyond US coastlines, further threatening already fragile regions of the world, it noted, adding that increased sea levels and storm surges threaten coastal regions, infrastructure and property.

A changing climate will act as an accelerant of instability around the world, exacerbating tensions related to water scarcity and food shortages, natural resource competition, underdevelopment, and overpopulation, it said.

"Thus, climate change impacts, coupled with other global dynamics, including growing and urbanising populations, could devastate homes, land and infrastructure. Climate change will exacerbate water scarcity and may lead to increases in food costs," the report said.

The pressures caused by climate change will influence resource competition, while placing additional burdens on economies, societies and governance institutions around the world.

Many governments will face challenges to meet even the basic needs of their people as they confront demographic change, resource constraints, effects of climate change and risks of global infectious disease outbreaks, it said.

"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. The risk of conflict may increase," the report warned.

According to the White House, the near-term impacts of climate change are likely to have a disproportionate effect on poor countries with weak governance structures, particularly in Africa and Asia.

"Because the United States is a global power with strategic interests around the world, climate change is strategically important to the United States through the impacts it has on the regional stability of US allies," the White House argued.

The report said climate change is predicted to strain economies and societies around the world, placing an additional burden on the already-vulnerable nations abroad and putting pressure on capacity at home.

"Climate change will change the nature of US military missions, demand more resources in the Arctic and other coastal regions vulnerable to rising sea levels and other impacts, and require a multilateral response to the growing humanitarian crises that climate change is predicted to bring," it said.

"While the challenges are vast, the United States is preparing with strong resilience measures that will address these changing dynamics, making the Nation safer at home and strengthening missions abroad," the White House said.