President Barack Obama issued 263 executive orders during his eight years in office, at least 35 of them dealing with climate change, energy or the environment. When President-elect Donald Trump takes office, revoking some of those executive orders could be among his first acts, because it can be done without Congress, by the simple stroke of a pen.

"On the first day of my term of office, my administration will immediately pursue" canceling "every unconstitutional executive action, memorandum and order issued by President Obama," Trump said in his 100-day action plan.

Trump has made it clear that among his top priorities is the unfettered development of America's oil, gas and coal. He pledged to revive the coal industry, although its decline is largely due to market forces, to lift restrictions and moratoriums on energy production, and to rescind regulations that stand in the way of this future. This clearly has put rules like the Clean Power Plan and methane regulations on the chopping block, but beyond that his agenda is still unclear.

"If you look at the substance of the Trump campaign, it was hard to know what specific policies he was referring to and what he was advocating," said Gary Bass, who founded the former government watchdog group OMB Watch. "So, I don't know what he's going to do. I have no clue. I wonder if he does?"

On executive orders, he has a lot of targets. The orders range from fighting climate change to making federal buildings greener to ensuring that climate change is taken into account on committees dealing with the economy and domestic policy.

Some deal with climate change only tangentially, with a single mention of climate or a low-carbon future in an order that deals with other issues. Others take the issue head on. They include requirements for federal buildings to be built based on more rigorous flood risk data; the establishment of a National Ocean Policy that would protect and coordinate decisionmaking related to oceans and coasts; the creation of committees to help disaster restoration efforts on the Gulf Coast and around the Chesapeake Bay; and mandates for the federal fleet to use lower-emitting vehicles.

(There are several that Trump is likely to keep, too, including one executive order established to mollify the pipeline industry and its Congressional backers during the fight over Keystone XL. That order expedites the regulatory process around oil and gas infrastructure and development projects.)

While it is impossible to know exactly what Trump will do when he takes office, a week after the election the conservative Competitive Enterprise Institute (CEI) gave a window into his possible thinking, when it laid out a hit list of three climate policy-related executive orders that it wants immediately eliminated. The leader of Trump's EPA transition team is Myron Ebell, CEI's director for its Center for Energy and Environment.

The executive orders identified by CEI all involve changing the way the federal government operates to deal with climate change:

Planning for Federal Sustainability in the Next Decade

This order, issued on March 19, 2015, calls for the reduction of each federal agency's greenhouse gas emissions by 40 percent over the next decade from 2008 levels and increases the share of electricity the federal government uses from renewables to 30 percent. The order achieves these gains by setting interim targets limiting energy use and sources in federal buildings, and lowering emissions from the federal fleet of vehicles.

Climate Resilient International Development

Issued on Sept. 23, 2014, this order mandates that international development work must factor in climate resilience. In its blog post, CEI wrote that this should be targeted because "elevating 'climate-resilience considerations' too easily becomes an excuse to deny poor countries access to affordable energy, ignore the real causes of poverty (corruption, lack of strong property rights), and legitimize phony grievances against the fossil energy-rich United States."

Preparing the United States for the Impacts of Climate Change

This order lays out a series of steps that federal agencies must take to help American communities strengthen their resilience to climate change. It was issued on Nov. 1, 2013. CEI took issue with this because it argued that "the order directs agencies to recruit, indoctrinate, bankroll, and coordinate climate activists at all levels."

Those aren't the only orders that could be on the chopping block. Others appear to be implementing Obama's climate agenda through executive order and have resulted in backlash from Republicans.

Stewardship of the Ocean, Our Coasts and the Great Lakes

This June 2010 order adopted the findings of the Interagency Ocean Policy Task Force and implemented a new National Ocean Policy and created a task force with the goal of protecting and restoring ocean habitats and ecosystems in the wake of the 2010 Deepwater Horizon spill.

The House Committee on Natural Resources' website had this to say about the order: "The policy sets up a new level of federal bureaucracy with control over the way inland, ocean and coastal activities are managed. This has the potential to inflict damage across a spectrum of sectors including agriculture, fishing, construction, manufacturing, mining, oil and natural gas, renewable energy, and marine commerce, among others."

Enhancing Coordination of National Efforts in the Arctic

This order from January 2015 established a steering committee to coordinate activities in the Arctic among federal, state, local, Alaska Native and all other stakeholders. It was issued as the United States was poised to take the leadership of the Arctic Council, an intergovernmental panel that coordinates the Arctic states.

Though it was lauded by many as a way to streamline work in the Arctic and make sure Alaska Natives were given a voice, not everyone was happy with it. In a statement issued at the time, Sen. Lisa Murkowski (R-AK) said, "Science-based decision making is essential as we move forward, but we cannot 'study' ourselves into inaction. Investment and vision are needed—in infrastructure, ice breakers, and a predictable federal oil and gas permitting process—to craft an Arctic economy."

Establishing a Federal Flood Risk Management Standard and a Process for Further Soliciting and Considering Stakeholder Input

This January 2015 order would have seemed like a natural target. It mandates that federal buildings meet higher flood risk management standards with decisions based on "a climate-informed science approach."

When it was released, the order sparked a backlash from conservatives. Eight Republican senators from among the most flood-prone states in the country sent a letter to Obama calling the order illegal and saying it would lead to unaffordable flood insurance rates. But when the 2016 omnibus budget was passed, it had much of the executive order's language tucked inside it. With Congress's stamp of approval behind it, the order is no longer so vulnerable.

There are also a number of executive orders that Trump and his allies are unlikely to reverse. They include:

Improving Performance of Federal Permitting and Review of Infrastructure Projects

This 2012 order was issued by Obama from the campaign trail that year, in front of a stack of pipelines in the oil hub of Cushing, Okla. It called for expedited permitting and review of infrastructure projects, including pipelines. It was designed to deflect Republican criticism for the president's first rejection of the Keystone XL pipeline.

Supporting Safe and Responsible Development of Unconventional Domestic Natural Gas Resources

Also issued in 2012, this order sought to expedite the regulatory process around developing natural gas. When the order was issued, the Natural Gas Supply Association sent out a glowing statement, saying "NGSA welcomes today's executive order, which should create an improved regulatory environment for natural gas development."