Some people believe that issues like climate change and pandemics can only be tackled if nations cooperate. I agree with this statement to a large extent, though I think action at national and local levels also plays a part.
The main reason is that these problems do not respect borders. Carbon dioxide released in one country warms the whole planet, and a virus can spread across continents within days through air travel. If one nation acts but its neighbours do nothing, the effort is largely wasted. Cooperation also allows resources and knowledge to be pooled. During the Covid-19 pandemic, scientists around the world shared genetic information about the virus, which enabled vaccines to be developed in record time, and richer countries funded programmes to distribute them. Shared rules, such as the Paris Agreement on emissions or international health regulations, create common standards and make it harder for any one nation to avoid its responsibilities.
Nevertheless, cooperation is difficult to achieve. Countries have different priorities; developing nations may be reluctant to restrict industrial growth, while wealthy ones are often unwilling to pay for changes elsewhere. Some governments also avoid commitments or ignore agreements once they are signed, since there is no authority that can force them to comply. For this reason, action within countries remains essential. Cities can improve public transport, companies can cut waste, and individuals can change their habits, all of which contribute to the wider goal.
Even so, I believe these local actions cannot be sufficient without a coordinated framework. They are most effective when they are encouraged by international targets and shared funding.
In conclusion, global problems demand joint solutions because their causes and consequences cross borders, and although national and local efforts matter, only international cooperation can deliver results on the necessary scale.