Offsetting policies have increased worldwide, utilizing a range of biodiversity metrics to compensate for development impacts. We conducted a global analysis of offset legislation by reviewing policies from 108 countries, which have voluntary offsets, or which require offsets by law. We sought to understand how well biodiversity metrics and offset currencies are documented in current policies. Where biodiversity metrics are documented we aimed to understand how metrics were scored, combined, and multiplied to create offset currencies. We found only 22 jurisdictions (from 14 countries) had guidelines documenting how biodiversity should be assessed during offsetting, representing a significant gap in the guidance available for offsets. Of the 22 guidelines, 14 (63%) documented use of aggregated currencies, eight (23%) did not aggregate biodiversity metrics into a single currency, and three (17%) did not specify either approach. Habitat type and condition, as well as area, were widely recommended across policies (>50%). Where species-level metrics were considered, guidelines generally focused on habitat distributions rather than abundance or population metrics. The lack of consistent and clear guidance about how biodiversity should be measured in offsets reduces our ability to determine the effectiveness of offsets in compensating for development impacts long term.

中文翻译：

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全球分析揭示了抵消政策透明度和生物多样性衡量方式方面的集体差距

世界范围内抵消政策有所增加，利用一系列生物多样性指标来补偿发展影响。我们通过审查 108 个国家的政策，对抵消立法进行了全球分析，这些国家有自愿抵消或法律要求抵消。我们试图了解当前政策中生物多样性指标和抵消货币的记录情况。在记录生物多样性指标的地方，我们旨在了解如何对指标进行评分、组合和相乘以创建抵消货币。我们发现，只有 22 个司法管辖区（来自 14 个国家）制定了记录在抵消期间如何评估生物多样性的指南，这表明可用于抵消的指南存在重大差距。在 22 项指南中，14 项 (63%) 记录了汇总货币的使用，八项 (23%) 没有将生物多样性指标汇总为单一货币，三项 (17%) 没有具体说明这两种方法。栖息地类型和条件以及面积在各项政策中得到了广泛推荐（>50%）。在考虑物种层面的指标时，指南通常侧重于栖息地分布，而不是丰度或种群指标。关于如何在补偿中衡量生物多样性，缺乏一致和明确的指导，这降低了我们确定补偿在补偿长期发展影响方面的有效性的能力。