FARMINGTON — American Indian tribes may be disproportionately affected by climate changes as compared to the general population, a National Wildlife Federation study found.

The study, released this month, found that American Indians and Alaska Natives in North America are more vulnerable to climate changes because they are more heavily dependent on natural resources and live closer to the land than does the general population.

"Extreme weather events can be very destructive for tribes, many of whom are already suffering from lack of resources to begin with," said Amanda Staudt, a senior scientist for the National Wildlife Federation. "Heat waves and droughts can exacerbate plant and wildlife mortality, heighten the risk of wildfires and habitat loss and compromise tribal lands."

Tribes depend on the land and natural resources to sustain economic, cultural and spiritual practices. They also face a relative lack of financial and technical resources needed to recover from extreme weather events, the study found.

"High rates of poverty and unemployment on reservations mean that tribes have limited resources to help their populations deal with weather and climate extremes, much less to adapt to a changing climate over the long term," the study states. "Because tribes are restricted by reservation boundaries, their attachment to the land and off-reservation treaty rights, moving to new areas to accommodate climate shifts is not a viable option."

Climate changes are defined as ecological shifts that can lead to weather extremes like severe drought and heat waves, wildfires and heavier rainfall and snowfall.

Locally, climate and weather changes have adversely affected individual residents on the Navajo Nation, and the population as a whole.

Ranchers who work a total of 350,000 acres of Navajo ranch land, located in New Mexico and Arizona, are struggling with drought conditions they say have stretched since 1978.

Ranchers across the Four Corners area are forced to sell their livestock earlier than usual this year because of the lack of precipitation, which ultimately means they are buying supplemental feed or losing money by selling scrawnier animals.

Although all ranchers in the Southwest are affected by one of the driest seasons in recent history, those on the Navajo Nation may be hit the hardest, said Vicki Atkinson, a brand inspector for the New Mexico Livestock Board. The reasons for that are limited resources and the isolated locations where ranchers are raising livestock.

"It's pretty normal to see livestock coming from the reservation that don't look good," said Atkinson, who is on hand every Monday at the Cow House in Kirtland, where she inspects livestock before they go to auction.

As many as 80 or 90 percent of all livestock that go through the Cow House come from ranchers on the various local American Indian reservations, Atkinson said. Ranchers have struggled with drought since 1995, she said.

"This year is especially bad," she said. "We have horses, cattle that are in critical condition, so people are selling earlier before they get too bad."

The Navajo Nation also experiences emergency weather conditions nearly every year when heavy snowfall in the winter or muddy conditions in the early spring mean residents in the most remote areas are stranded at home without passable roads or the resources to call for help.

"Power disruptions from storms, long dry spells and heavy floods can be difficult to recover from, especially for people who live close to the land and have limited economic resources," Garrit Voggesser, senior manager for the National Wildlife Federation Tribal Lands Program, said during a teleconference with journalists Aug. 3.

"Extreme weather events are destructive and recovery costs are great, which will further burden Indian tribes more than others due to their lack of infrastructure, capacity and financial support to address these challenges," he said.

Yet tribes exhibit significant resiliency and strength to meet those challenges, the study found.

"Indian tribes have an opportunity to build on their close connection to (the) land, traditions of sustainability and resilience to navigate a way for the changes of the coming decades," Voggesser said.

The National Wildlife Federation released the study in collaboration with the Tribal Lands Program, Institute for Tribal Environmental Professionals, National Congress of American Indians, Native American Fish & Wildlife Society, National Tribal Environmental Council, Native American Rights Fund and the University of Colorado Law School.

The study asks Congress to increase funding to allow the Bureau of Indian Affairs to seek solutions.

It also stresses the need for the federal government to enforce tribal rights to natural and cultural resources and calls on tribes to use their sovereign authority to address climate change and plan appropriately.

"More than many other peoples, native peoples understand the importance of robust natural systems," Kim Gottschalk, staff attorney for the Native American Rights Fund, said during the teleconference. "All of us must act to prohibit the disproportionate harm to Native Americans brought on by climate change."

The study identifies these specific climate-related issues on tribal land:

Extreme droughts weaken trees. On the nation's 326 reservations, there are approximately 18.6 million forested acres. Droughts also lower water levels and impair agricultural productivity.

Water scarcity in the West further complicates tribes' unresolved water rights claims.

Because springs are warmer and summers drier, wildfires have increased four-fold since the mid-1980s, the fire season is 78 days longer and individual fires are 30 days longer.

Flooding from heavy rain, snowmelt, melting sea ice and rising sea levels destroys homes, building, and infrastructure and can increase diseases and parasites. Two U.S. General Accountability Office studies found that more than 200 Alaska Native villages were affected by flooding and erosion and 31 villages should consider relocating because of imminent threats. Yet recovery costs can be insurmountable for tribes.

Some areas like the upper Midwest and Northeast will see more record-breaking, intense snowstorms that can paralyze communities and damage homes and infrastructure.

Climate change is breaking down natural mechanisms that help wildlife and habitat survive weather variations. For example, the U.S. Environmental Protection Agency has projected significant loss of stream habitat for trout and salmon.