What better day than Earth Day -- the 43rd incarnation -- than to ask where President Obama’s environmental record stands at this point in his presidency, and what are the most important decisions that lie ahead of him during his second term.

First, let's look at where he has taken action.

1. Reducing pollution from cars and light trucks. The administration has taken two major steps to clean up the U.S. passenger vehicle fleet. First, the Environmental Protection Agency and Transportation Department have cut greenhouse gas emissions from cars and light trucks, demanding that by 2025 the U.S. auto fleet must average 54.5 miles per gallon. Then, late last month, EPA proposed imposing stricter fuel and equipment standards on American autos that would reduce the amount of sulfur in U.S. gasoline by two-thirds and impose fleet-wide pollution limits on new vehicles by 2017. Car manufacturers have supported these initiatives, while oil refiners have opposed them as imposing too heavy a cost on their industry.

2. Curbing harmful emissions from power plants. EPA has taken aim at utilities--many of which are powered by coal and have been operating for more than 30 years--on multiple fronts. In December 2011 the agency  required coal- and oil-fired power plants to control emissions of mercury and other poisons for the first time. The rule, which was two decades in the making, applies to about 40 percent of the country’s roughly 1,400 coal- and oil-fired utilities that lack modern pollution controls. A year later it tightened the nation’s soot standards by 20 percent, reducing the sort of fine particle pollution leading to heart and lung disease. And on Friday EPA issued new rules limiting the kind of water utilities can discharge from hundreds of power plants. These rules, along with other initiatives aimed at governing mine waste disposal, have prompted many coal industry officials and their allies in Congress to accuse the administration of waging a "War on Coal."

3. Adopting a broad policy for managing the nation's ocean waters. Just last week the administration finalized its National Ocean Policy, which aims to coordinate the work of more than two dozen agencies and reconcile competing interests including fishing, offshore energy exploration and recreational activities.

4. Supporting renewable energy development. President Obama touts the fact that the amount of U.S. renewable energy doubled during his first four years in office. The administration has given billions of dollars to the wind, solar and geothermal industries through both direct subsidies and in the form of tax credits, and it has worked to streamline the permitting process on public lands and in federal waters. At least 10,000 megawatts of onshore renewable energy has been permitted on federal land already. Renewable industry advocates have embraced these policies while Republicans point to the failure of Solyndra, the solar manufacturer which cost taxpayers more than $500 million, as an example of why the U.S. shouldn't provide financial backing for this industry.

Now to what the Obama Administration is in the midst of doing related to the environment.

1. The first-ever greenhouse gas emission limits for power plants. A year ago EPA proposed a new standard greenhouse gas standard would have required any new power plant to emit no more than 1,000 pounds of carbon dioxide per megawatt hour of electricity produced; a week and-a-half ago the agency said it would delay finalizing the rule, as it is still reviewing more than 2 million comments on it.

2. A new smog rule. In September 2011, Obama decided to pull back an EPA proposal to limit ozone emissions linked to smog, on the grounds that it would hurt the economy and the government would revisit the issue in 2013 anyway. This year the agency must identify its new smog standard, which would improve air quality but potentially limit economic development in regions across the country.

3. Regulating coal ash waste. Produced by 431 coal-fired power plants, which supply 36 percent of the nation’s electricity, coal ash piles up at the rate of 140 million tons a year. The EPA has been looking at this issue ever since. Nearly three years ago the agency outlined three possible rules for storing and disposing of coal ash, but none have become final. The first would designate it a hazardous waste; the other two would regulate it as a solid waste.

And now, what the Administration may or may not do.

1. A presidential permit for the Keystone XL pipeline project. Sometime this year, likely in the fall, the State Department will have to decide if it will let TransCanada build a pipeline that crosses the Canada-U.S. border. Proponents said the pipeline is the safest and most efficient way to transport crude oil from Canada's oil sands region to Gulf Coast refineries, while generating short-term, high-paying  construction jobs and ensuring a steady oil supply from one of our closest allies. Critics argue it will speed development of a carbon-intense form of oil that will exacerbate climate change, and could still spill on ecologically-sensitive habitat. Obama is likely to weigh in personally on the decision, which has been the subject of intense political debate for more than two years.

2. Curbing greenhouse gas emissions from existing power plants. More than any other action, the single biggest climate policy Obama could undertake would be to impose limits on greenhouse gas emissions from utilities now in operation. The president has not yet said whether he will pursue this course, but EPA has given every indication it plans to pursue this policy in concert with the states over the course of the next year. No matter what the administration does, this will provoke a major political and legal battle.

3. Weigh in on whether large-scale mining operations can take place in Alaska’s Bristol Bay watershed. EPA is now reviewing whether a proposed gold mine near Alaska's Bristol Bay would harm wild salmon habitat so significantly it should invoke the Clean Water Act to declare the area off-limits. Backers of the mining project proposed by Northern Dynasty Minerals, a Canadian company, say it would be inappropriate for EPA to weigh in before the firm formally requests a permit.

As a second-term president, Obama is under intense pressure to deliver to the environmental constituency that helped him win reelection last fall. CREDO Mobile political director Becky Bond, whose group is lobbying against the Keystone pipeline, wrote in an e-mail, "If President Obama approves the Keystone XL pipeline over all of the scientific evidence, it will be remembered by history just as poorly as President Bush’s invasion of Iraq, which was based on deceptive information and burdened us with enormous financial and human cost."

And Sen. Sheldon Whitehouse (D-R.I.), said in a statement that while the president's investment in clean energy and vehicles rules have been significant "he can't stop there."

“President Obama has said that failing to respond to climate change would ‘betray our children and future generations,’ and I know he strongly believes that," Whitehouse said. "I hope the President continues to follow through on his commitment to address climate change, including establishing carbon pollution standards for new and existing power plants and setting efficiency standards for appliances."

Even Luke Popovich, a spokesman for the National Mining Association, said Obama is in a tough position when it comes to reconciling his economic and environmental goals.

"He is in an unenviable position," Popovich wrote in an e-mail, "trying to rescue the economy and help the millions shut out of the job market at the same time he wrestles with environmental issues that could aggravate the problem if taken too far."