Washington announced on Friday its formal return to the Paris climate agreement, just 107 days after it left. Describing the occasion as "a day of hope", UN Secretary-General Antonio Guterres said that he was particularly pleased to be commemorating the event with John Kerry, the US special presidential envoy for climate.

Indeed, as the world's largest developed country and one of the major greenhouse gas emitters, the absence of the US from the accord and its four years of inaction under the previous administration has undoubtedly greatly compromised the global endeavor to address climate change.

The Trump administration announced its withdrawal from the agreement in 2019, but it did not become effective until Nov 4, 2020 because of provisions in the agreement.

The return of the US to the agreement is welcome and important but its departure did a disservice to what the world could have achieved over the past four years. Just as Christiana Figueres, the former UN climate chief, said: "It's not about how many days. It's the political symbolism that the largest economy refuses to see the opportunity of addressing climate change. We've lost too much time."

What the world hopes is the Joe Biden administration fully appreciates that its predecessor's wrong decision has cost the world dearly in its efforts to contain the global temperature rise. In other words, the US, as one of the major greenhouse gas emitters, owes the world a great deal for its failure to do what it should have done over the past four years.

The world also hopes that while the Biden administration is demonstrating that it aims to reassert US leadership in international affairs by re-entering this important international agreement, it has abandoned the mentality that the US can manipulate international organizations for its own benefit or ride rough shod over other countries in pursuit of its own interests.

Instead, the US needs to recognize that the national action plans laid out in the Paris Agreement are what each country needs to do for the future of mankind. So it needs to mean what it says about its targets in reducing the amount of carbon dioxide it emits. It also needs to honor its promises to extend aid including funds, technology and capacities to developing countries in their endeavor to reduce greenhouse gas emissions.

As the world's largest economy, the US has every reason to set a good example by looking at climate change's threat to human survival through the prism of the common interests of the international community rather than that of the US only.

The US should also set an example for all developed countries in observing the principle of common but differentiated responsibilities in honoring their obligations in helping their developing counterparts realize sustainable development and efforts to address climate change.