## 3 Results and Discussion
### Publications and International Collaboration
#### 3.1.2 International Collaboration  
To further analyze the influence of each country in this field, we employed VOSviewer to investigate the network relationship diagram of the top 50 countries by publications (Figure 3a). In this diagram, each node (sphere) represents a country. Taking the United States and China as examples, their co-appearance in articles establishes a link between their respective nodes, with the frequency of such co-occurrences reflecting the link strength of their collaboration. The total link strength for the United States across all countries in this network diagram serves as a metric of its collaborative engagement. Among the top three countries by total link strength--namely, the United States, Germany, and China--their respective strengths are 2643, 1502, and 1417. Additionally, the color gradient of all nodes from deep blue to yellow represents the average citations received by articles involving each country, known as average citations. Among the top three countries by publications, Germany has the highest average citation at 97, followed by the United States and China with citations of 83 and 41, respectively. Detailed data on the total link strength, average citations, and other metrics for the top 10 countries can be found in Supplementary Table S2.  
Climate change is a pivotal topic for international collaboration [36; 37]. To delve deeper into the temporal dynamics of international cooperation, we augmented the original dataset with four additional subsets spanning from 2000 to 2011, and then 2014, 2017, and 2020. These subsets aimed to explore changes in collaboration patterns between typical developed and developing countries, with the United States and Germany representing major developed countries, and China and India representing major developing countries. As is shown in Figure 3b, two green lines illustrate the evolution of collaboration between the United States and China. It is shown that these two green lines exhibit a converging trend, indicating a decrease in the proportion of China-USA cooperation for China, while showing an increasing for the United States. The two orange lines display a slow declining trend, signifying a decrease in collaboration proportion for both Germany and the United States in our topic area. Meanwhile, the two blue lines show a slight upward trend, suggesting a modest increase in collaboration proportion between China and India. These findings suggest a shift in international collaboration dynamics in this field, transitioning from the initial dominance of developed countries to an increasing influence of major developing countries, thereby fostering more diversified collaboration. The growing influence of developing countries in scientific research within the climate field is a beneficial trend, considering their significant role in mitigating climate change [38]. The link strength between USA-China, USA-Germany, and China-India provides quantitative insights into the collaboration between these major countries. Detailed data on the overall link strength,individual link strength, and the percentage of link strength for the USA, Germany, China, and India can be found in Table S3.