with Brazil and the northern border is the Atlantic coast. The southernmost borders with French Guiana and Guyana are disputed by these countries along the Marowijne and Corantijn rivers, respectively, while a part of the disputed maritime boundary with Guyana was arbitrated by the Permanent Court of Arbitration convened under the rules set out in Annex VII of the United Nations Convention on the Law of the Sea on 20 September 2007. Climate Lying two to five degrees north of the equator, Suriname has a very hot and wet tropical climate, and temperatures do not vary much throughout the year. Average relative humidity is between 80% and 90%. Its average temperature ranges from . Due to the high humidity, actual temperatures are distorted and may therefore feel up to hotter than the recorded temperature. The year has two wet seasons, from April to August and from November to February. It also has two dry seasons, from August to November and February to April. Climate change in Suriname is leading to warmer temperatures and more extreme weather events. As a relatively poor country, its contributions to global climate change have been limited. Because of the large forest cover, the country has been running a carbon negative economy since 2014. Biodiversity and conservation Due to the variety of habitats and temperatures, biodiversity in Suriname is considered high. In October 2013, 16 international scientists researching the ecosystems during a three-week expedition in Suriname's Upper Palumeu River Watershed catalogued 1,378 species and found 60—including six frogs, one snake, and 11 fish—that may be previously unknown species. According to the environmental non-profit Conservation International, which funded the expedition, Suriname's ample supply of fresh water is vital to the biodiversity and healthy ecosystems of the region. Snakewood (Brosimum guianense), a tree, is native to this tropical region of the Americas. Customs in Suriname report that snakewood is often illegally exported to French Guiana, thought to be for the crafts industry. On 21 March 2013, Suriname's REDD+ Readiness Preparation Proposal (R-PP 2013) was approved by the member countries of the Participants Committee of the Forest Carbon Partnership Facility (FCPF). As in other parts of Central and South America, indigenous communities have increased their activism to protect their lands and preserve habitat. In March 2015, the "Trio and Wayana communities presented a declaration of cooperation to the National Assembly of Suriname that announces an indigenous conservation corridor spanning