President Biden is facing one of the biggest political challenges of his first 100 days: Convincing both sides of the climate change debate that he’s serious about tackling the global issue.

The President is hosting a virtual climate summit on Thursday with 40 leaders from around the world in which he’s expected to declare a specific but nonbonding goal for reducing U.S. greenhouse gas emissions by 2030. But it’s the target he sets that observers say will show his hand on the climate change issue, and prove if his administration will actually take the steps necessary to attack the issue with what he has described in the past as “the urgency science demands.”

At this week's climate summit hosted by the White House, the Biden administration is expected to promise to sharply reduce American greenhouse gas emissions and to help poorer countries pay for the costs of climate change. https://t.co/CnXsOV7hSY

— NPR Politics (@nprpolitics) April 19, 2021

Climate change is an incredibly divisive issue even by today’s polarizing standards. It’s also incredibly expensive and much more abstract than the two primary issues the Biden White House has focused on: Battling the pandemic and infrastructure.

The level of emissions reduction that Biden sets will be “setting the tone for the level of ambition and the pace of emission reductions over the next decade,″ according to an AP interview with Kate Larsen, a former White House adviser who helped develop President Obama’s climate action plan.

Adding to the urgency is that the next decade is seen by most scientists and other experts on the topic as being incredibly important if we want to slow down climate change.

Biden is expected to announce a target goal to reduce our greenhouse gas emissions by at least 50% below 2005 levels by 2030. Anything less than that, and environmental advocates will say Biden is reneging on his promise to enact a real strategy to combat the climate crisis.

Of course, trying to hit that goal would mean major changes in the power and transportation sectors, including ramping up the use of renewable energy sources such as wind and solar power. Republicans already decry Biden’s climate intentions as a foolhardy plan that will cost too many American jobs. But those on the other side are also watching intently to see what Biden does.

After four years where former president Trump essentially dismissed climate change, the hope was that Biden would lead the charge to course-correct the planet’s environmental erosion. His infrastructure bill aims to provide significant investment in a clean-energy transition program, one that the White House says would create lots of high-paying jobs. His actions at Thursday’s summit will reveal if some people will still believe in that promise