Perhaps the question means: what is the difference in count of species B now versus then? But it says how many more — implies positive. - Parker Core Knowledge

Understanding the Context

Counting species helps track biodiversity, a key indicator of planetary health. Every species plays a role in maintaining ecological balance—from pollination and nutrient cycling to disease regulation. Understanding species count changes over time allows researchers to identify trends, assess human impact, and inform effective conservation strategies.

Comparing Species Counts: Past vs. Present

The Big Picture: Loss and Gain — But Net Fragmented

Key Insights

Historically, Earth teemed with vastly greater biodiversity. Fossil records and ecological reconstructions show that pre-human or pre-industrial times hosted richer and more stable species populations. Since the Industrial Revolution and especially in recent decades, habitat destruction, climate change, pollution, and invasive species have driven massive declines. Many species have gone extinct, and others face severe population drops.

Yet, in some regions and taxonomic groups, new species discoveries—often thanks to modern DNA analysis and field surveys—indicate modest gains or stable populations. For example, new insect or fungal species might be formally identified each year, signaling that scientific efforts continue to uncover biodiversity even amid crises.

Numerical Comparison: A Complex Picture
Exact counts vary widely. Global assessments estimate current species richness as around 8.7 million, with only about 1.2 million described—leaving up to 7 million undocumented. By contrast, paleontological data suggest roughly 5–10 million species once inhabited Earth. The modern era has a net decline of several million species, though precise figures remain elusive due to incomplete records.

The phrase “how many more” implies a positive change—an increase in counts. However, statistically, total species numbers have overwhelmingly declined. Growth, when measured, typically occurs in smaller subsets (like newly documented species or taxon numbers within resilient groups), not the ecosystem as a whole.

Final Thoughts

Key Factors Influencing Species Count Shifts

1. Extinction Rates:
   Anthropogenic pressures—deforestation, urban sprawl, and pollution—have accelerated extinction rates hundreds to thousands of times above natural background levels. Many species vanish before being documented.

2. Discovery and Taxonomy Updates:
   Advances in genetic sequencing and biodiversity surveys mean researchers formally declare more species each year. This discovery doesn’t reverse losses but enriches our understanding.

3. Ecosystem Resilience:
   Some ecosystems resist change longer, maintaining higher species counts temporarily. However, cumulative stressors eventually erode even these strongholds.

Why It Matters for Conservation