Climate change is one of the most critical issues in the 2020 Democratic presidential primaries, and each candidate is eager to prove that he or she is the right person to address the crisis. Ten Democrats are appearing at a town hall hosted by CNN on Wednesday, a six-hour event which provides candidates with ample opportunity to explain their climate plans.

Most candidates have the goal of achieving net-zero greenhouse gas emissions by 2050, although some aim to accelerate by a few years to 2040 or 2045. Many candidates also hope to cut emissions by half by 2030 or get to net-zero emissions for electricity by that year. All candidates have also pledged to rejoin the Paris Climate Accords, the international non-binding agreement from which President Trump withdrew shortly after taking office.

Michael Gerrard, a professor at Columbia Law School and founder and director of the Sabin Center for Climate Change Law, told CBS News it was unrealistic to expect the U.S. to reach net-zero electricity emissions by 2030. He also recommended looking at how candidates would use executive action to combat climate change, as a Democratic president may have to contend with a combative Republican majority in the Senate.

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"The most important thing to be looking for in the candidate statement is how they can use their executive powers," Gerrard said. "They themselves cannot write trillion dollar checks. Throwing out very large dollar signs that probably wouldn't be passed by Congress anyway is not especially meaningful."

Joe Biden, Cory Booker, Pete Buttigieg, Julián Castro, Kamala Harris, Amy Klobuchar, Beto O'Rourke, Bernie Sanders, Elizabeth Warren and Andrew Yang are the candidates who will be appearing at the town hall.

Here's a primer on where the candidates' climate plans stack up so far.

Joe Biden

Biden's climate plan, which he introduced in June, anticipates that the U.S. will achieve a 100% clean energy economy and net-zero greenhouse gas emissions by 2050. He also embraces the Green New Deal as a "crucial framework" for future plans to address climate change.

Biden's plan includes spending $1.7 trillion over 10 years, with over $5 trillion in additional investments from the private sector and local and state governments. Other parts of the plan include:

Implementing legally binding emissions reduction targets;

Investing over $400 billion over 10 years in clean energy to create new jobs;

Providing incentives for farmers and companies to use more energy efficient practices; and

Ensuring the federal procurement system purchases 100% clean energy and zero-emissions vehicles.



Full details about Biden's plan can be found on his website.

Cory Booker

Booker's plan would invest $3 trillion through 2030 to build an economy with net-zero emissions by 2045 and end all federal subsidies for fossil fuel companies. His proposal would also ban fracking and institute a carbon fee with the goal of having net-zero emissions for electricity by 2030. Other parts of his plan include:

Investing over $100 billion by 2030 through existing Department of Agriculture conservation programs to make farms more sustainable;



Investing $400 billion in research and development throughout the country;

Revoking Mr. Trump's executive orders to approve the Keystone Pipeline and the Dakota Access Pipeline; and

Increasing EPA enforcement actions against polluters.

Full details about Booker's plan can be found on his website.

Michael Bennet

Bennet's plan would aim for the U.S. to achieve 100% clean energy and net-zero greenhouse emissions by 2050. His proposal would also create a "Climate X Option," which would require every power provider to offer every household the option to purchase low-cost zero-emission electricity. The Climate X Option would also include tax incentives for states to provide Americans with zero-emission transportation. Other parts of the plan include:

Committing to conserving 30% of U.S. lands and oceans by 2030;

Launching the "2030 Climate Challenge" allowing states to compete for federal infrastructure funding by reducing emissions;

Creating a "Climate Bank" to spur $10 trillion in investment from the private sector in clean energy innovations; and

Creating the "Next Generation Climate Board of Directors" comprised of youth leaders to have young people's input on the subject.

Full details about Bennet's plan can be found on his website.

Steve Bullock

Although his campaign climate plan is not as thorough as some other candidates' proposals, Bullock has the ambitious goal of having net-zero emissions by 2040. Bullock's plan also includes having each government agency develop a plan to reduce carbon emissions each year. Other parts of the plan include:

Strengthening automobile fuel efficiency regulations;

Directing the Departments of Interior and Agriculture to achieve net-zero emissions on public lands by 2030;

Ending the influence of special interest groups that represent the energy industry; and

Setting realistic emissions reduction targets for the U.S. military.

Full details about Bullock's plan can be found on his website.

Pete Buttigieg

Buttigieg released his climate change plan ahead of the climate town hall on Wednesday. He says his goal to get to net-zero emissions by 2050.

To do this, Buttigieg's plan calls for doubling clean electricity production in the US by 2025, requiring zero emissions for passenger vehicles ten years after that and net-zero emissions for larger vehicles -- such as ships and aircraft -- by 2040. By 2050, Buttigeig says the U.S. can achieve net-zero emissions from the manufacturing and agricultural sectors.

The plan also calls for putting a price on carbon that would increase each year, with the revenue returned to Americans via rebates. Buttigieg's administration would also invest $200 billion dollars over 10 years in federal R&D for clean energy. Buttigieg also wants rural Americans to be involved in combatting climate change by supporting soil carbon sequestration -- which would look to trap more CO2 in soil -- and investing in the Department of Agriculture's R&D programs to promote sustainability.

Buttigieg also has committed to rejoining the Paris Climate Accords.

Julián Castro

Under Castro's climate plan, his first executive action as president would be to rejoin the Paris Climate Accords. He has also set a goal of achieving net-zero greenhouse emissions by 2045 and halving the emissions level by 2030. The first two parts of Castro's comprehensive plan call for ending fossil fuel extraction on public lands and ending taxpayer subsidies for fossil fuel production. Other parts of the plan include:

Establishing a $200 billion Green Infrastructure Fund to support public transportation and improving energy efficiency in buildings;

Creating a National Climate Council to coordinate the federal government's action on climate change;

Passing civil rights legislation to address environmental discrimination, such as in Flint, Michigan, where a majority-black population was exposed to extremely high levels of lead in its water; and

Expanding HUD's competitive National Disaster Resilience Grant program with $500 million in annual funding

Full details about Castro's plan can be found on his website.

Bill de Blasio

De Blasio's campaign website does not include proposals for what he would do if president, but it does include a page on "Accomplishments" during his tenure as New York City mayor. The achievements listed include doubling investments in climate solutions to $4 billion, signing an executive order committing New York City to the goals of the Paris Climate Agreement, and achieving emissions reductions as part of the city's Green New Deal.

De Blasio has also claimed that he oversaw the divestment of $5 billion out of fossil fuel holdings from the city's pension fund. However, Politico reports that the city has not divested any funds from the fossil fuel industry but has only announced its intentions to study the issue.

John Delaney

Delaney rolled out a $4 trillion proposal to address climate change in May, including a major tax on carbon emitters and a plan to redistribute the funds to Americans. Most of his plan — $3 trillion — would be funded by the carbon tax, which he calls the "Carbon Fee and Dividend" proposal. His proposal also includes increasing the budget for the Department of Energy green energy programs and creating a "Climate Corps," which would send volunteers to low-income areas to the support the development of a greener economy in these communities.

Full details about Delaney's plan can be found on his website.

Tulsi Gabbard

Although Gabbard does not have a specific proposal listed on her website, the congresswoman from Hawaii has called climate change a "personal" issue for her.

"First of all, this is personal. You can imagine I grew up in Hawaii, which is the most remote island chain in the world, so for us growing up there, protecting our environment was not a political issue — it's a way of life," Gabbard said in the second Democratic debate.

Gabbard told the New York Times in April that she hoped to achieve 100% clean energy in the U.S. by 2035. She has also touted her OFF Fossil Fuels Act which she introduced in Congress, which provides a road map for achieving this goal.

Kamala Harris

Harris has outlined a $10 trillion plan to address climate change with the aim of having net-zero emissions by 2045 and 100% carbon-neutral electricity by 2030. Like many other candidates, Harris emphasizes climate justice in her plan, and stresses the importance of the Climate Equity Act to address the issue. She would also go after major polluters, ending federal subsidies for fossil fuel production and requiring corporations to pay a climate pollution fee.

Other parts of her plan include:

Developing a Clean Building Standard to ensure that new infrastructure is energy efficient

Creating clean energy jobs, particularly for former fossil fuel workers

Ending all fossil fuel development on public lands

Conserving 30% of the country's lands and ocean by 2030

Amy Klobuchar

Klobuchar also supports achieving net-zero carbon emissions by 2050 and restoring the goals of the Clean Power Plan put in place by President Obama, which set emissions standards for states. Other parts of her plan include:

Investing in green jobs as part of her $1 trillion infrastructure plan;

Strengthening federal climate research;

Expanding access to clean energy in rural areas; and

Creating state, local and private incentives to use clean energy.



Full details about Klobuchar's plan can be found on her website.

Beto O'Rourke

O'Rourke's plan would mobilize $5 trillion in new investments to address climate change over 10 years, beginning with $1.5 trillion funded by "structural changes to the tax code," ending tax subsidies for fossil fuel companies and raising tax rates on corporations. His plan would also invest $250 billion in research and development and include clean energy job training. Other parts of his plan include:

More than $1.2 trillion in grants for developments such as sustainable housing, transportation, public health and farming;

Guaranteeing net-zero emissions by 2050 and halving emissions by 2030; and

Increasing spending on environmental disaster mitigation efforts.

Full details about O'Rourke's plan can be found on his website.

Tim Ryan

Ryan has not released a formal plan to address climate change, but has discussed investing in clean energy jobs to help address the issue.

"We should dominate the electric vehicle market. We should dominate the battery market. We should dominate the charging station market," Ryan said in the first Democratic debate, suggesting that workers once employed by coal mines or automakers could make a transition to green jobs.

On his website, Ryan notes that there will be almost 30 million electric cars on the road by 2030. "This stuff has to get built somewhere and I want everything built right here in the United States," he wrote.

Bernie Sanders

Sanders has proposed his version of the "Green New Deal," a $16.3 trillion plan to combat climate change which would start by declaring the phenomenon a national emergency. The price tag for Sanders' plan is significantly higher than those of other candidates.

Sanders' plan aims to reach 100% renewable energy for electricity and transportation by 2030, and zero-net emissions by 2050. His proposal also includes "ending unemployment" by creating 20 million jobs to address climate change, and helping transition fossil fuel workers to green energy. Other parts of his plan include:

Rejoining the Paris Climate Accord and providing $200 billion to help other countries reach emissions targets;

Providing a $40 billion Climate Justice Resiliency Fund to address how climate change has affected low-income and minority communities in the U.S.;

Investing in research and development related to climate change; and

Investing in conservation and public lands.

Full details about Sanders' plan can be found on his website.

Tom Steyer

Billionaire Steyer has a five-pillar "Justice-Centered Climate Plan" which aims to address climate change by assisting vulnerable communities. His goal includes ending "global warming pollution" by 2045 and eliminating toxic air pollution by 2030. Like Delaney, Steyer also wants to implement a "Civilian Climate Corps," which his website describes as "a combined service, training, and job creation effort."

Other parts of his plan include:

Investing $50 billion in local economies and expanding and restoring public areas;

Investing in energy efficient infrastructure; and

Improving the disaster response system.

Full details about Steyer's plan can be found on his website.

Elizabeth Warren

Warren, who is known for her granular policy plans on several topics, has introduced proposals for fighting climate change using the military, investing $2 trillion in green manufacturing and requiring companies to disclose climate-related risks. She would also stop fossil fuel extraction on public lands. Her goal for the military includes having the Pentagon achieve net zero-carbon emissions for all non-combat bases and infrastructure by 2030.

Another climate proposal would spend $1.5 trillion in federal procurement for American-made low-carbon technology, aid to help foreign countries buy American-made clean energy technologies, and a "Green Apollo Program" for investing $400 billion into clean energy research and development.

Full details about Warren's plans can be found on her website.

Marianne Williamson

Williamson had received some of the largest applause at the second debate when she noted that many Americans have experienced "environmental injustice."

"We have an administration that has gutted the Clean Water Act. We have communities, particularly communities of color and disadvantaged communities all over this country, who are suffering from environmental injustice," Williamson said.

Williamson's focus on environmental justice is seen in her plan to address climate change. Like most other candidates, she supports having net-zero emissions by 2050. She also supports halting all new fossil fuel projects and providing federal incentives for renewable energy. Other parts of her plan include:

Banning all fracking operations;

Requiring corporations to follow emissions standards; and

Restarting the Clean Power Plan to transition the economy away from coal.

Full details about Williamson's plan can be found on her website.

Andrew Yang

Yang, the entrepreneur whose plan to implement universal basic income launched him into the tier of competitive candidates, has a plan to pledge $4.9 trillion in "climate-related" spending over 20 years. His plan includes an aggressive timeline: establish zero-emissions standards for buildings by 2025, have zero-emissions standards for all cars by 2030, have a 100% renewable energy grid by 2035, have net-zero emissions for all transportation by 2040, and achieve net-zero emissions overall by 2049. His plan also includes investing in nuclear energy, which unlike fossil fuels, does not release any carbon emissions into the atmosphere.

Yang also has the controversial idea to invest in relocating Americans who would be affected by rising sea levels. This includes $40 billion in relocation or home elevation subsidies, and $30 billion for infrastructure such as seawalls to protect coastal cities.

Full details about Yang's plan can be found on his website.