Learning from climate change news: Is the world on the same page?

Splitting To be able to evaluate the classification and regression models, not all available data was used for training. First, 20% of the data was randomly split off as Test set, i.e. data left unseen by all models and used for the final evaluation. The remaining 80% was further split into a Train set for training the models during experiments and a Dev set for evaluating these experimental models, again randomly and with an 80%-20% ratio. This translates as 64% and 16% of all data respectively. In the end, the combined Train-Dev set was used to train the final model, since the Test set was available for evaluation. For each split, a random seed was used to ensure ran- domness while keeping reproducibility. The label distributions in each subset of the data were verified to be roughly consistent and true to the distribution in the original dataset. Features The main features were word and character n-grams. These were represented by tf-idf rele- vance scores. For each model, tf-idf scores were calculated over the whole corpus using TfidfVectorizer (scikit-learn.org/stable/modules/generated/sklearn.feature_extraction. Table 2. Overview of the distributions for the country and political orientation labels. Country Political orientation COP meeting United Kingdom Australia Canada Left-Center Right-Center Total COP1 227 271 363 616 245 861 COP2 269 371 300 494 446 940 COP3 309 591 653 958 595 1,553 COP4 403 363 552 830 488 1,318 COP5 263 361 412 523 513 1,036 COP6 427 305 350 668 414 1,082 COP6a 351 468 415 667 567 1,234

COP7 344 467 453 710 554 1,264 COP8 288 360 374 546 476 1,022 COP9 364 437 340 640 501 1,141 COP10 258 392 289 535 404 939 COP11 558 545 442 826 719 1,545 COP12 673 1,087 469 1,209 1,020 2,229 COP13 758 1,045 615 1,380 1,038 2,418 COP14 575 968 391 1,037 897 1,934 COP15 1,136 1,531 517 1,642 1,542 3,184 COP16 715 814 331 1,015 845 1,860 COP17 718 840 402 1,087 873 1,960 COP18 797 663 323 942 841 1,783 COP19 825 710 308 1,115 728 1,843 COP20 981 629 350 1,283 677 1,960 COP21 1,695 866 507 2,080 988 3,068 COP22 752 522 290 827 737 1,564 COP23 626 549 268 759 684 1,443 COP24 1,107 627 352 1,036 1,050 2,086 COP25 1,268 676 361 1,274 1,031 2,305 Average 642 633 401 950 726 1,676 Total 16,687 16,458 10,427 24,699 18,873 43,572 https://doi.org/10.1371/journal.pone.0297644.t002 PLOS ONE Learning from climate change news PLOS ONE | https://doi.org/10.1371/journal.pone.0297644 March 20, 2024 10 / 27